Synonyms for Masterly:

adj.

cunning (adjective)
devious, smooth, snaky, clever, crafty, ingenious, serpentine, scheming, cunning, deft, shrewd, designing, wily, slippery, wary, feline, masterful, witty, canny, sly, skillful, subtle, calculating, sharp, artful, tricky, quick, astute, slick, foxy.
expert (adjective)
master.
superior (adjective)
masterful, excellent, superb, consummate, proficient, skillful.

adv.

sagaciously (adverb)
intelligently, authoritatively, intellectually, wisely, brilliantly, sagaciously, expertly, adeptly, philosophically.
supremely (adverb)
Paramountly, Consummately, lordly, dominantly, chiefly, Sovereignly, eminently, Commandingly, predominantly, Superiorly, supremely, signally, Capitally.

adv

sagaciously (adverb)
intelligently, authoritatively, intellectually, wisely, brilliantly, sagaciously, expertly, adeptly, philosophically.
supremely (adverb)
Paramountly, Consummately, lordly, dominantly, chiefly, Sovereignly, eminently, Commandingly, predominantly, Superiorly, supremely, signally, Capitally.

n.

skillfully, nice, barnstorming, tight. crackerjack, ability, expert, proficient, adept, professional, master. masterly (noun)
masterful, consummate, virtuoso, skilled.

Other synonyms:

nice, barnstorming, crackerjack. proficient, tight, adept. professional. master. first class
excellent.
Other relevant words:
skilled, superb, excellent, consummate, adept, virtuoso, crackerjack, skillfully, expert, barnstorming, professional, master, proficient.

Usage examples for masterly

  1. The puzzle is, how did this masterly observer know that this state of affairs existed between this couple? – Ways of Nature by John Burroughs
  2. A horse leaps away with strong, terrified action, there is a masterly grasp of his vivid subject, and a rugged strength in the execution which gives great life to it. – Fra Bartolommeo by Leader Scott (Re-Edited By Horace Shipp And Flora Kendrick)
  3. A masterly pie, Bertie, and it wasn't more than half finished. – Right Ho, Jeeves by P. G. Wodehouse