What was it about that obnoxious, obstreperous and obstinate
obstetrician? Why did she keep obstructing me with her obsolete
and obvious observations? Her obscene and obdurate obsession
with the obscure would soon obligate me to obtain an order to
The obvious common factor in many of the words in the preceding
paragraph is the word fragment ob; even without knowing
immediately what it might mean, many of the words carry a suggestion
of contrariness, subtraction, or burden. Can we say any more
than that, though?
The prefix ob comes from Latin; of course it comes as a prefix
of a Latin root, and so we have to know both the meaning of ob
and of the Latin root word to try to work out the etymology of a given
In many "ob-words", the prefix has a meaning of "contrary",
"against", or even "across from". Thus,
obambulate has the root ambulare or "walk",
and means to walk around something.
obbligato has the root ligare or "bind", and an obbligato
is a musical direction indicating that a certain portion of the music
must be played.
obdurate (obduracy) has the root durare or "harden",
so an obdurate person is "hard against" one;
obfirm has the root firm or "harden", and to
obfirm something is to harden its resistance;
obfuscate has the root fuscare or "darken", so to
obfuscate is to "bring darkness onto" something;
obituary has the root itire or ire, meaning
"to go", and comes from a phrase meaning "to meet (come across)
object has the root iacere or "throw", so to object is
to "throw against" one;
oblate has the root latus which is the past participle
of ferre, a word for "carry", and so an oblate object
has been "carried toward" something - this word is used to describe
a sphere that has been somewhat squeezed or flattened between
obligate has the root ligare or "bind", and to obligate
someone is to "bind them to" some requirement;
obliterate has the root litera meaning "letter", and
suggests rubbing out the letters of a document; a second suggested
etymology refers to the root oblivisci, meaning "to forget";
obloquy has the root loqui, meaning "to speak",
and so obloquy is "speech against" something.
obnoxious has the root noxius or "harmful", so to be
obnoxious is to "bring injury to" something;
obnubilate has the root nubus or "cloud", so to obnubilate
is to cover with clouds, or to make obscure;
obrotund has the meaning of being originally rounded, but
obscure has the root scurus or "cover", so to
obscure is to "cover over" something;
obsession has the root sidere meaning "to besiege",
and an obsession is something that besieges you;
obstacle has the root stare or "stand still",
so an obstacle "stands against" one; the Latin phrase
Nihil obstat, was used by the Catholic Church to indicate
that a book had nothing objectionable; the phrase
literally means "nothing against-standing".
obstetrics has the root stare or "stand",
so an obstetrician "stands across from" the woman giving birth;
obstinate has the root stinare or "stand" or "persist",
so an obstinate person "persists against" one;
obstipation has the root stipare meaning "to compress",
and refers to severe constipation caused by obstruction.
obstreperous has the root strepere or "make noise", so
an obstreperous person "makes noise against" one;
obstruct has the root struere or "pile up",
so an obstruction is "piled up against" one; similarly, an
obstruent consonant is a consonantal sound made by
obstructing the flow of air.
obtect has the root tegere meaning "cover", and
describes wings or other appendages on a butterfly or moth that
have been covered over by a secretion that forms a shell or case.
obtenebrate has the root tenebere meaning "darken", and
means to cast a shadow over something;
obtrude has the root trudere meaning "to thrust", and
something is obtrusive when it "pushes against" one.
obtuse has the root tundere or "beat" or "pound",
so an obtuse thing has been "beaten against", and includes the
related word obtund;
obumbrate shares the root "umbra" with "umbrella" and "penumbra",
and means to "overshadow".
obvention has the root venire meaning "to come", and
means an incidental occurrence, something that "comes across"
obverse has the root vertere meaning "to turn" and so
the obverse is "turned toward" one (and the reverse is not!);
obviate has the root via meaning
"road" or "path"; to obviate a difficulty is to find a way across
or around it;
obvious has the root via meaning
"road" or "path"; something is obvious when it is right there in
oubliette comes to English from French, but has the same
etymology as obliterate; an oubliette is a horrible type of deep, thin
dungeon with an opening at the top, in which you can toss someone
that you more or less want to "forget about";
In some "ob-words", the prefix has a meaning of intensification.
obtain has the root tenere or "hold", and to obtain
something is to "completely hold onto it";
oblong has the root longus or "long", and to an oblong
thing is "very long";
In some other words, the role of ob is not so clear, and we
are left only with the underlying root. Thus,
obese has the root edare meaning "to eat";
obey (obedient, obedience) has the root audire meaning
"to hear" and so an obedient person is one who "hears toward"
obeisance, a bow or nod of respect, comes from the same root
objurgate has the root jurgare meaning "to quarrel",
and so to objurgate is to "quarrel with (against)" someone.
oblivion has the root levis meaning "smooth", and
so to oblivate is to "smooth over";
obscene may come from the root caenum meaning "filth";
an alternative explanation suggests that it indicates theatrical
action that must occur "behind the scenes".
obsequy ha the root sequus
meaning "to follow", and so an obsequy is the last duty
performed for a person after their death;
obsequious haa the root sequus
meaning "to follow", and so an obsequious
person is someone who "follows after" or is eager to
be a follower;
observant has the root serve or "to keep", "to guard",
"to watch", and so to be observant is to "watch over".
obsolete has the root solescere meaning "to become
obturate has the root obturare, and
is similar in meaning to obstruct, and means to
block passage through something. It is often used to describe
the way a bullet, which is slightly smaller than the chamber,
expands upon firing to fit the chamber snuggly.
oppidan is a term used at a medieval university to describe
nonresident students, who were instead townspeople, or residents
of a university town who were not students. Apparently, the
root ped is involved in the derivation, and the Latin
word was oppidum meaning town.
And in some "ob-words", time and usage have worn the
word down so that the ob isn't even completely there!
occasion has the root cadere or "to fall";
occident has the root cadere or "to fall", and
indicates the direction towards which the sun sets;
occiput (occipital) has the root cipitus or
caput, meaning "head";
occlude has the root claudere or "to shut";
occult has the root culere or "to cover";
occupy has the root cupare or capere,
occur has the root currere or "run";
offend (offense) has the root fendare or "strike";
offer has the root ferre or "carry";
omit (omission) has the root mittere or "send";
opaque for which the root is not clear;
oppignorate, meaning to offer a pledge;
oppilate, meaning obstructed by hairs or fibers.
Being opened, the cerebral vessels were found oppilated,
with all the symptoms of a congestion of the blood towards
opportune (opportunity) has the root portus or "port";
and is supposed to suggest that, like a boat coming into harbor,
things are working out favorably.
oppose (opposite, opposition, opponent) has the root
ponere or "place"; "op-posite" and "ap-posite" illustrate
how the prefixes and root work together.
oppress has the root primere or "press";
opprobrium has the root probrum, a disgraceful act;
surely "op-probium" and "ap-proval" are illustrating modifications
of the same root.
oppugn has the root pugnare or "fight";
and means to fight against, and oppugnacity is the
corresponding tendency to fight against things, to rebel.
ostensible has the root tendare or "show";
and suggests that something has been done merely for show.
ostentatious has the root tendare or "show";
the ob- prefix has been almost slurred away, but
to be ostentatious is to "show off" something;
ostent also has the root tendare or "show";
and signifies a sign or wonder; it's clearly related to
portent as well.
Words that might be suspected of this root, but which are actually
"innocent bystanders" include obelisk, obsidian, office,
osculate and oscillate.
In Penelope Lively's book "Consequences", I ran across the word
obstruse which is plainly not an obs word, but a variant
spelling of abstruse. Oddly enough, in the same book she
repeatedly refers to apposition of two things when I expected that
she meant opposition.
Among its many contrivances, the Museum of Jurassic Technology in
Los Angeles has an extensive exhibit about Geoffrey Sonnabend, and his
theory of memory and forgetting described in the book Obliscence.
It may be appropriate to mention some related Latin phrases, which crop
up in English from time to time:
obiter dictum, a legal term referring to remarks made in a
judicial statement, that addresses issues beyond those directly
involving the case at hand. The word iter means "the way" or
"the journey" or "the road", and so the etymology is echoed in the
common phrase "by the way";
nihil obstat, a phrase printed at the beginning of a book that
has been submitted to, and approved by, Roman Catholic religious
authorities. The words mean "nothing objectionable"; the
obstat is directly related to the root of "obstinate", so
that there is "nothing standing against" the printing of this book.
And you may now proceed on your way, with no further obstructions,
and let these obscure observations seek their obligatory oblivion.
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Last revised on 29 May 2014.