Synonyms for First:

adj.

beginning (adjective)
embryonic, original, aboriginal, fetal, inaugural, alpha, beginning, formative, preparatory, sprouting, Dawned, incipient, new, infantile, Commencing, primeval, preliminary, germinal, foremost, early, infant, newborn, emerging, primordial, baby, introductory, maiden, precursory, initiatory, initial, Inceptive, budding, hatching, genesis, nascent, starting, primal.
earliest (adjective)
original, primordial, maiden.
older (adjective)
firstborn.
original (adjective)
innovative, authentic, prototypical, original, ingenious, creative, unique, initial, genuine, novel.

adv.

all (adverb)
foremost, firstly, first of all, first off.
at the beginning (adverb)
to begin with, initially.

adv

at first (adverb)
initially.
firstly (adverb)
to begin with, at first under first, initially.
originally (adverb)
to begin with, at first.

n.

chief, principal, the fact (of the matter) is, at the end of the day, importantly, basically, not just any..., essentially, in essence, preeminent, mainly. barely, by the time, pioneer, advance, previous, Since, before, earlier. from the get-go, front end, all along, at first. creator, creative commons, originator, author, progenitor, visionary, engineer, inventor. automobile, jumper cables, defrost, car wash, auto, body shop, lube job, the AAA, jump leads. ideal, there is no substitute for something, unsurpassed, first-rate, first class, second to none, incomparable, par excellence. beginning (noun)
alpha.
communication (noun)
First-class Honours Degree.
first (noun)
first gear, beginning, premiere, prototypic, 1st, number one, freshman, maiden, best, archetypal, archetypical, first-year, eldest, prototypal, start, top, opening, kickoff, original, first of all, First-class Honours Degree, prime, basic, forward, inaugural, initiative, oldest, initiatory, outset, low, first off, offset, firstly, starting time, introductory, firstborn, number 1, foremost, initial, first base, for the first time, prototypical, ordinal, commencement, premier, low gear.
linkdef (noun)
number one.
opening (noun)
kickoff.

Other synonyms:

basically, front, barely, earliest, the AAA, importantly, jump leads, body shop, best, car wash, previous, principal, auto, lube job, defrost, automobile, Since, jumper cables, earlier. key, before, main, paramount, top. major. prime. advance. earliest
primary.
first
leading.
first-class honours degree
First-class Honours Degree.
principal
capital.

Usage examples for first

  1. I got him first that's all. – They of the High Trails by Hamlin Garland
  2. But first you must take this- and then you must talk to me. – Marcella by Mrs. Humphry Ward