of, pertaining to, or occurring at the beginning; first

the initial step in a process.

Phonetics . occurring at the beginning of a word or syllable, as the (k) sound of kite, chasm, or quay.

an initial letter, as of a word.

the first letter of a proper name.

a letter of extra size or an ornamental character used at the beginning of a chapter or other division of a book, manuscript, or the like.

to mark or sign with an initial or the initials of one's name, esp. as a token of preliminary or informal approval.

adverb

at the beginning , originally , first