early 15c., repugnaunce, "logical contradiction, inconsistency; incompatibility; resistance, opposition"(senses now obsolete), from Old French repugnance "opposition, resistance" (13c.) or directly from Latin repugnantia "incompatibility," from stem of repugnare "resist, disagree, be incompatible," from re- "back" (see re-) + pugnare "to fight" (from PIE root *peuk- "to prick"). The meaning "mental opposition or antagonism, aversion, strong dislike" is from 1640s. Related: Repugnancy.
early 15c., repugnaunt, "hostile, opposed; contrary, inconsistent, contradictory," from Old French repugnant "contradictory, opposing" or directly from Latin repugnantem (nominative repugnans), present participle of repugnare "to resist, fight back, oppose; disagree, be incompatible," from re- "back, against, in opposition" (see re-) + pugnare "to fight" (from PIE root *peuk- "to prick").
The meaning "distasteful, objectionable" is from 1777; that of "offensive, loathsome, exciting aversion" is by 1879.
There are many theories to explain the Latin sense development, but none has yet been generally accepted; de Vaan suggests the sense is "cause to remain in existence." Originally in English especially of religion; sense of "unreasonable notion" is from 1794.
early 15c., "armed encounter, battle," from Old French conflit and directly from Latin conflictus "a striking together," in Late Latin "a fight, conflict," noun use of past participle of confligere "to strike together, be in conflict," from assimilated form of com "with, together" (see con-) + fligere "to strike" (see afflict).
Meaning "a struggle, a quarrel" is from mid-15c. Sense of "discord of action, feeling, or effect, clashing of opposed principles, etc." is from 1875. Psychological sense of "incompatible urges in one person" is from 1859 (hence conflicted, past-participle adjective); the noun was used from 15c. in the sense "internal mental or spiritual struggle" (against temptation, etc.). Phrase conflict of interest was in use by 1743.