Opposite, contradictory, contrary, antithetical, antipodal, antipodean, antonymous are comparable chiefly as applied to abstractions and as meaning so far apart as to be or to seem irreconcilable with each other.
The same differences in applications and implications are found in their corresponding nouns, opposite, contradictory, contrary, antithesis, antipode, antonym , when they mean one of two things which are opposite or contradictory. Opposite is the inclusive term; it may be used interchangeably with any of the others, though few of the others are interchangeable in precise use.
Opposite may be used to describe the relation of either of two abstract elements (as ideas, terms, statements, qualities, or forces) to the other when they are set against each other so as to bring out sharply the contrast, conflict, or antagonism between them.
Contradictory, though often used as an equivalent of opposite, may retain its fundamental implication of denial, and therefore, especially when it is applied to terms, propositions, and principles, may further imply that if one of the two opposites be true, the other must be false, or if one be false, the other must be true.
Words, propositions, or principles that are contradictory in this strict sense are mutually exclusive and, therefore, admit no possibilities between; thus, "John is English" and "John is not English" are contradictory statements, one of which must be false if the other is true; alive and dead are contradictory terms because they cannot both be truly applied to the same thing.
Contrary (see also CONTRARY 2 ) as applied to intentions, motives, and opinions usually implies extreme divergence with no basis for agreement.
But especially as applied to terms and propositions contrary may imply diametrical opposition or the greatest conceivable or possible difference between the things opposed. Contraries are poles apart; unlike contradictories both may be false, for they represent extremes and do not mutually exclude every other possibility; thus, destitute and opulent are contrary terms as applicable to a person's circumstances, but they may be inapplicable in a vast number of particular cases for they describe only the extremes; "John is parsimonious" and "John is prodigal" are contrary statements, but John in truth may be neither parsimonious nor prodigal, but merely close, or thrifty, or free, or liberal, in the expenditure of money.
Antithetical and especially antithesis (see also COMPARISON ) imply an intent to set the thing under consideration against its opposite, usually its diametrical opposite, in order to emphasize its significance or to reveal or define sharply its true nature. Both words are applicable to persons and things regarded objectively as well as to ideas, qualities, and terms.
Although antipodal or antipodean and the corresponding noun, antipode, which often occurs as the plural antipodes with singular or plural construction, also imply diametrical opposition, they do not suggest a logical relation but rather emphasize the unlikeness and the remoteness from each other of the things contrasted. So strong are these implications that often the things contrasted are only figuratively, not generically, opposites, and the contrast constitutes in a sense an inverse simile.
Antonymous and antonym are applicable only to a word or term which is so opposed to another in meaning that it, in effect, negates or nullifies every implication of it. Antonyms or antonymous words may be contradictory or contrary terms, as defined, or they may be terms which negate other terms by implying the undoing or reversing of what is denoted by them; thus, retain is the contradictory antonym of lose, but recover is the reverse antonym of lose.