allege (v.) Look up allege at Dictionary.com
c. 1300, "make a formal declaration in court;" mid-14c., "pronounce positively, claim as true," with or without proof; it has the form of one French verb and the meaning of another. The form is Anglo-French aleger, Old French eslegier "to clear at law" (from a compound of Latin ex "out of;" see ex- + litigare "bring suit" (see litigation).

However eslegier meant "acquit, clear of charges in a lawsuit," and the Middle English word somehow acquired the meaning of French alléguer, from Latin allegare/adlegare "send for, bring forth, name, produce in evidence, send on business," from ad "to" (see ad-) + legare "to depute, send" (see legate). Related: Alleged; alleging.