vest (v.) Look up vest at Dictionary.com
early 15c., "to put in possession of a person," from Middle French vestir, from Medieval Latin vestire "to put into possession, to invest," from Latin vestire "to clothe," related to vestis "garment, clothing," from PIE *wes- "to clothe" (see wear). Related: Vested; vesting.
vest (n.) Look up vest at Dictionary.com
1610s, "loose outer garment" (worn by men in Eastern countries or in ancient times), from French veste, from Italian vesta, veste "robe, gown," from Latin vestis, from vestire "to clothe" (see vest (v.)). The sleeveless garment worn by men beneath the coat was introduced by Charles II.
The King hath yesterday, in Council, declared his resolution of setting a fashion for clothes .... It will be a vest, I know not well how; but it is to teach the nobility thrift. [Pepys, "Diary," Oct. 8, 1666]