Of or pertaining to the beginning; incipient: as, the initial step in a proceeding.Placed at the beginning; standing at the head: as, the initial letter of a word, or of a chapter in a book.n. The initial or first letter of a word; an initial letter.n. The first letter of a book or writing, or of any division of it, distinguished from the body of the text by larger size or more ornamental character, or both.n. In plain-song, a tone with which a melody may begin. In strict usage the initials for each mode are prescribed, and called absolute initials.To put one's initial or initials to or on; sign or mark with initials: as, an initialed handkerchief; initialed paper.n. In steam-engines, an abbreviation of initial pressure (which see).