Initialled

[ih-nish-uh l] /ɪˈnɪʃ əl/

adjective
1.
of, relating to, or occurring at the beginning; first:
the initial step in a process.
2.
Phonetics. occurring at the beginning of a word or syllable, as the (k) sound of kite, chasm, or quay.
noun
3.
an initial letter, as of a word.
4.
the first letter of a proper name.
5.
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.
verb (used with object), initialed, initialing or (especially British) initialled, initialling.
6.
to mark or sign with an initial or the initials of one’s name, especially as a token of preliminary or informal approval.
/ɪˈnɪʃəl/
adjective
1.
of, at, or concerning the beginning
noun
2.
the first letter of a word, esp a person’s name
3.
(printing) a large sometimes highly decorated letter set at the beginning of a chapter or work
4.
(botany) a cell from which tissues and organs develop by division and differentiation; a meristematic cell
verb -tials, -tialling, -tialled (US) -tials, -tialing, -tialed
5.
(transitive) to sign with one’s initials, esp to indicate approval; endorse
adj.

1520s, “of or pertaining to a beginning,” from Middle French initial or directly from Latin initialis “initial, incipient,” from initium “a beginning, an entrance,” from past participle stem of inire “to go into, enter upon, begin,” from in- “into, in” (see in- (2)) + ire “to go” (see ion).
v.

“to mark or sign with initials,” 1864, American English, from initial (n.). Related: Initialed; initialing.
n.

“initial letter of a name or surname,” 1620s, from initial (adj.) in a specialized sense “standing at the beginning of a word, sentence, etc.”