inverse(n = noun.linkdef) opposite - something inverted in sequence or character or effect; "when the direct approach failed he tried the inverse"
is a kind of oppositeness, opposition
has particulars: additive inverse, multiplicative inverse, reciprocal

1.  inverse(s = adj.all) reverse - reversed (turned backward) in order or nature or effect;

2.  inverse(a = adj.all) - opposite in nature or effect or relation to another quantity; "a term is in inverse proportion to another term if it increases (or decreases) as the other decreases (or increases)"
Antonym: direct

1.  Opposite in order, relation, or effect; reversed; inverted; reciprocal; -- opposed to direct. [1913 Webster]

2.  Inverted; having a position or mode of attachment the reverse of that which is usual. [1913 Webster]

3.  Opposite in nature and effect; -- said with reference to any two operations, which, when both are performed in succession upon any quantity, reproduce that quantity; as, multiplication is the inverse operation to division. The symbol of an inverse operation is the symbol of the direct operation with -1 as an index. Thus sin-1 x means the arc or angle whose sine is x. [1913 Webster]

   That which is inverse. [1913 Webster]
"Thus the course of human study is the inverse of the course of things in nature." [1913 Webster]

inverse, adj. & n.
--adj. inverted in position, order, or relation.
--n.
1 the state of being inverted.
2 (often foll. by of) a thing that is the opposite or reverse of another.
3 Math. an element which, when combined with a given element in an operation, produces the identity element for that operation.

Idiom:
inverse proportion (or ratio) a relation between two quantities such that one increases in proportion as the other decreases. inverse square law a law by which the intensity of an effect, such as gravitational force, illumination, etc., changes in inverse proportion to the square of the distance from the source.

Derivative:
inversely adv.

Etymology:
L inversus past part. of invertere: see INVERT

N  inversion, eversion, subversion, reversion, retroversion, introversion, contraposition, contrariety, reversal, turn of the tide, overturn, somersault, somerset, summerset, culbute, revulsion, pirouette, transposition, transposal, anastrophy, metastasis, hyperbaton, anastrophe, hysteron proteron, hypallage, synchysis, tmesis, parenthesis, metathesis, palindrome, pronation and supination, inverted, wrong side out, wrong side up, inside out, upside down, bottom upwards, keel upwards, supine, on one's head, topsy-turvy, sens dessus dessous, inverse, reverse, opposite, top heavy, inversely, hirdy-girdy, heels over head, head over heels.

N  contraposition, opposition, polarity, inversion, opposite side, reverse, inverse, counterpart, antipodes, opposite poles, North and South, antonym, opposite (contrariety), opposite, reverse, inverse, converse, antipodal, subcontrary, fronting, facing, diametrically opposite, Northern, septentrional, Boreal, arctic, Southern, Austral, antarctic, over, over the way, over against, against, face to face, vis-a- vis, as poles asunder, contraposition, opposition, polarity, inversion, opposite side, reverse, inverse, counterpart, antipodes, opposite poles, North and South, antonym, opposite (contrariety), opposite, reverse, inverse, converse, antipodal, subcontrary, fronting, facing, diametrically opposite, Northern, septentrional, Boreal, arctic, Southern, Austral, antarctic, over, over the way, over against, against, face to face, vis-a- vis, as poles asunder.

additive inverse, inverse cosecant, inverse cosine, inverse cotangent, inverse function, inverse secant, inverse sine, inverse tangent, multiplicative inverse