Webster's Revised Unabridged Dictionary · 1913

Am

Am ({not transcribed})

[Anglo-Saxon am, eom, akin to Gothic im, Icelandic em, Olr. am, Lithuanian esmi, Latin sum., Greek {not transcribed}, Zend ahmi, Sanskrit asmi, from a root as to be. {not transcribed}. See Are, and compare Be, Was.]

The first person singular of the verb be, in the indicative mode, present tense. See Be.
God said unto Moses, I am that am. — Exod. iii. 14