Synonyms for Master:

adj.

expert (adjective)
crackerjack, ace, experienced, masterly, proficient, skillful, skilled, adept.
main (adjective)
foremost, predominant, ascendant, prevalent, supreme, leading, predominate, major, sovereign, principal, controlling, chief, paramount.
master (adjective)
commanding, directing, ruling, leading, star, senior, head, governing, Presiding, principal.
sagacious (adjective)
philosophic, intelligent, expert, sagacious, wise, genius, authoritative, brilliant, scholarly, adept, intellectual.
superior (adjective)
superior, better, most, choice, ruling, leading, furthermost, paramount, furthest, best, consummate, ascendant, eminent, king, senior, uppermost, above, champion, supreme, signal, predominant, quintessential, maximum, zenith, A 1, Headmost, chief, commanding, chosen, crowning, foremost, controlling, dominant, sovereign, elite.
universal (adjective)
common, collective, general, ubiquitous, omnipresent, universal, mass, generic, prevalent.
veteran (adjective)
patriarchal, veteran, senior, experienced, expert.

n.

excellent, develop, acquaint yourself with something, train, major, pick up, main, keep up, retrain. headman, hierarch, over, exponent, honcho. conquistador, certificate, dossier, confidentiality agreement, company report, Consent Form, document, conqueror, Annual Report, concept statement, blue book, charter. exercise, call off, heel, ability, proficient, dab hand, litter, dab, ace, past master, kitty litter, answer to, handler, domesticate, cat litter, kennel. employer, dictator, prototype, enforcer, figurehead, start, autocrat, demagogue, father, protoplast, the Establishment. jujitsu, judo, masterly, karate, martial art, skilled, belt, black belt, Kung Fu, masterful, skillful. conceal, deal with, keep back, bottle up. dude, bud, sonny, mate, BRO, sport, man, buddy, buster, son. chancellor, governing body, lunch lady, bursar, guidance counselor. on paper, circular, valid, textual, in black and white, written, returnable, enclosed, newsy, unanswered. housemaster, houseparent, headteacher, faculty. merchant marine, first officer, merchant seaman, first mate, merchant navy. be able to do something, have an eye for, have/get something down to a fine art, have a genius for (doing) something, can do something in your sleep, have a magic touch, be no slouch, be in practice, have a flair for something. artist (noun)
entertainer, sculptor, picasso, michelangelo, composer, dancer, musician, craftsman, artisan, rembrandt, author, singer, painter, performer.
artists (noun)
cartoonist, caricaturist, the Bloomsbury Group, impressionist, futurist, the avant-garde, draftsman, classicist, illustrator.
chieftain (noun)
headman.
director (noun)
magistrate, baron, overseer, administrator, overlord, ringleader, queen, band master, supervisor, warden, foreman, ringmaster, taskmaster, mayor, general, conductor, superintendent.
disciplinarian (noun)
enforcer.
expert (noun)
wizard, adept, buff, connoisseur, maven, journeyman, whiz, specialist, sophisticate, consultant, artist, technician, professional, pro, crackerjack.
expert, skilled person, female or male (noun)
genius, wizard, maestro, doctor, whiz, buff, champion, old hand, connoisseur, winner, prima donna, artist, sage, virtuoso, professional, savant, victor, maven, past master, authority.
master (noun)
headmaster, headmistress, lord, captain, governor, commandant, commander, titleholder, mother, director, star, abbot, executive, landlady, mandarin, landlord, quartermaster, squire, president, dean, leader, kingpin, manager, mahatma, proprietor, sire, maestro, head, principal, officer, ruler, proprietress, guru, authority.
original (noun)
protoplast.
person in charge, female or male (noun)
governor, superintendent, commandant, supervisor, captain, commander, guide, ruler, taskmaster, boss, head, tutor, employer, owner, lord, overlord, instructor, director, patriarch, pro, administrator, general, overseer, manager, guru, conqueror, teacher.
possessor (noun)
landlady, proprietress.
sage (noun)
savant, wise person, thinker, sage.
servants (noun)
footman, amah, housemaid, handmaiden, houseboy, domestic service, girl, butler, cabin boy, help.
superior (noun)
wonderwoman, aristocracy, nobility, paragon, prodigy, prize winner, superwoman, winner, virtuoso, premier, champ, exceller, victor, superman, prima donna.
teacher (noun)
educator, mentor, advisor, schoolmistress, tutor, guide, schoolmaster, instructor, trainer, teacher, counselor, coach, lecturer.
veteran (noun)
old-timer, patriarch, old soldier, old hand, gray-beard.

v.

cognition (verb)
control.
command (verb)
reign, grip, discipline, coordinate, hold, charge.
defeat (verb)
capture, outdo, humble, checkmate, overthrow, subdue, outplay, crush, win, surmount, defeat, rout, trump, overpower, subject, foil, overturn, triumph, quell, vanquish, whip, conquer, overcome, beat, trounce.
direct (verb)
direct, boss, lead, supervise, rule, oversee, govern, conduct, manage, superintend, administer, command.
influence (verb)
empower, authorize, motivate, sway, prejudice, predominate, influence, control, power, pressure, affect, bias.
learn (verb)
discover, assimilate, grasp, understand, realize, read, glean, digest, learn, study, absorb, comprehend.
learn; become proficient (verb)
grasp, study, pick up, comprehend, understand.
master (verb)
govern, command, head, lead, manage, rule, preside, direct.

Other synonyms:

headman, merchant marine, jujitsu, conquistador, merchant navy, guidance counselor, possessor, honcho, employer, first officer, martial art, develop, karate, governing body, Kung Fu, retrain, protoplast, bursar, conceal, train, judo, dictator, past master, black belt, merchant seaman, bottle up, dab hand, hierarch, first mate, lunch lady. chancellor, ace, prototype, masterly, keep up, proficient, keep back, conqueror, man. holder, exponent, skillful. masterful. domesticate, deal with. belt, father. proprietor
owner.
Other relevant words:
main, chancellor, past master.