• Webster's Revised Unabridged Dictionary
    • Obversion (Logic) The act of immediate inference, by which we deny the opposite of anything which has been affirmed; as, all men are mortal; then, by obversion, no men are immortal. This is also described as “immediate inference by privative conception.”
    • Obversion The act of turning toward or downward.
    • ***
Century Dictionary and Cyclopedia
    • n obversion The act of obverting or turning toward some person or thing, or toward a position regarded as the front.
    • n obversion In logic, same as conversion, or the transposition of the subject and predicate of a proposition.
    • n obversion In logic:
    • n obversion The taking of the contranominal of the inverse.
    • ***
Chambers's Twentieth Century Dictionary
    • n Obversion the act of turning toward the front of anything: in logic, a species of immediate inference—viz. the predicating of the original subject, the contradictory of the original predicate, and changing the quality of the proposition—e.g. to infer from all A is B that no A is not B—also called Permutation and Equipollence
    • ***


Webster's Revised Unabridged Dictionary
L. obversio, a turning towards
Chambers's Twentieth Century Dictionary
L. obversusob, towards, vertĕre, to turn.


In literature:

He was the obverse of Enjolras.
"Les Misérables Complete in Five Volumes" by Victor Hugo
This reverse side belongs to God; the obverse side to men.
"Seraphita" by Honore de Balzac
This being granted, it remains only to state and illustrate the obverse fact.
"The Unseen World and Other Essays" by John Fiske
Here is the obverse and the reverse of that empty and ugly thing called popularity.
"The Pocket R.L.S. Being Favourite Passages from the Works of Stevenson" by Robert Louis Stevenson
There was no obverse.
"Women in Love" by D. H. Lawrence
Now this lady and her husband were in obverse relative positions.
"Evan Harrington, Complete" by George Meredith
She was, in fact, the reverse of the medal of which poor Lady Rowley filled the obverse.
"He Knew He Was Right" by Anthony Trollope
You know but one side of the medal, Hypatia, and the fairer; I have seen its reverse as well as its obverse.
"Hypatia" by Charles Kingsley
The two views are very similar in character, one being the obverse of the other.
"The Lands of the Saracen" by Bayard Taylor
This is a world that allows nothing without its obverse and reverse.
"The Grandissimes" by George Washington Cable

In news:

Cash and Dylan, a Columbia Records superstar in the 1970s–is something of the obverse of Mr Cash .
The coin's front, or obverse, is unchanged, with a likeness of the President.
This Thursday, April 19, 2012, shows the obverse side of a rare 1792 experimental penny on display in Schaumburg, Ill.
6-1/2 Carbon steel clip point blade, cast aluminum handle with simulated stag texturing, marked MURPHY COMBAT on the obverse side and U.S.A. on the reverse side.
This Thursday, April 19, 2012 photo shows the obverse side of a rare penny on display in Schaumburg, Ill.

In science:

Obverse that many phenomena in the theory of stochastic processes, finance and hydrology are recently described through fractional evolution equations, see [6, 7, 30, 33] and the references therein.
On fractional powers of generators of fractional resolvent families
Type II error, except for one definition below (viii), has usually been treated instead in terms of its obverse, power.
Recent developments towards optimality in multiple hypothesis testing
As long as the strands are coloured normally, the reverse (so viewed) is just the colour-complement of the obverse and so is of no particular interest (‘obverse’ and ‘reverse’ rather than ‘front’ and ‘back’ because of the arbitrariness of which is which, as of a coin).
Isonemal prefabrics with only parallel axes of symmetry
Another unique state with three distinct Ma jorana spinors – constructed through a permutation symmetric superposition of two up qubits and one down qubit (W state) and its obverse state ( ¯W) exhibits genuine three-party entanglement, which is robust under loss of a qubit.
Interconvertibility and irreducibility of permutation symmetric three qubit pure states
However the reef knot is the trefoil connect summed with the reverse of its obverse, and so is slice.
A Second Order Algebraic Knot Concordance Group