early 15c., "small service book used by a priest," from Old French manuel "handbook" (also "plow-handle"), from Late Latin manuale "case or cover of a book, handbook," noun use of neuter of Latin manualis "of or belonging to the hand; that can be thrown by hand," from manus "hand, strength, power over; armed force; handwriting," from PIE root *man- (2) "hand." Meaning "a concise handbook" of any sort is from 1530s. The etymological sense is "small book such as may be carried in the hand or conveniently used by one hand."