What is the X in X-mas?
masc. proper name, from French Henri, from Late Latin Henricus, from German Heinrich, from Old High German Heimerich, literally "the ruler of the house," from heim "home" + rihhi "ruler." One of the most popular Norman names after the Conquest.
henry hen·ry (hěn'rē)
n. pl. hen·rys or hen·ries (-rēz)
The unit of inductance in which an induced electromotive force of one volt is produced when the current is varied at the rate of one ampere per second.
unit of either self-inductance or mutual inductance, abbreviated h (or hy), and named for the American physicist Joseph Henry. One henry is the value of self-inductance in a closed circuit or coil in which one volt is produced by a variation of the inducing current of one ampere per second. One henry is also the value of the mutual inductance of two coils arranged such that an electromotive force of one volt is induced in one if the current in the other is changing at a rate of one ampere per second. See inductance.