mid-15c., "so-called, not legitimate," past-participle adjective from pretend (v.).
"willful and persistent resistance to legitimate authority," c. 1200, from Old French contumace and directly from Latin contumacia "perseverance in one's purpose or opinions," generally in a bad sense, "arrogance, inflexibility, haughtiness, insolence," also especially "obstinate disobedience to a judicial order," abstract noun from stem of contumax (see contumely).
"want of loyalty, unfaithful behavior," early 15c., disloialte, from a variant of Old French desloiaute, desleauté "disloyalty, faithlessness, marital infidelity," from desloial, desleal "treacherous, false, deceitful" (Modern French déloyal), from des- "not, opposite of" (see dis-) + loial "of good quality; faithful; honorable; law-abiding; legitimate, born in wedlock," from Latin legalem, from lex "law" (see legal). Since c. 1600 especially "violation of allegiance or duty to a state or sovereign."
early 15c. (implied in disloyally), "not true to one's allegiance" (to a sovereign, state, or government), from Old French desloial, desleal "treacherous, false, deceitful" (Modern French déloyal), from des- "not, opposite of" (see dis-) + loial "of good quality; faithful; honorable; law-abiding; legitimate, born in wedlock," from Latin legalem, from lex "law" (see legal). Sometimes also "not true to one's obligations or engagements," especially to a lover, spouse, or friend, (late 15c.), but this sense is rare.