IHS Definition

Jesus (Greek ɪΗΣΟΥΣ with S for sigma)
American Heritage
A contraction derived from the Greek word ΙΗΣΟΥΣ, Jesus, used as a symbol or monogram: later misunderstood as a Latin abbreviation I.H.S. and expanded variously as Iesus Hominum Salvator, Jesus, Savior of Men; In Hoc Signo (Vinces), in this sign (thou shalt conquer); In Hac (Cruce) Salus, in this (cross) salvation.
Webster's New World
Indian Health Service - a Federal US agency.