perfectly (adv.)

c. 1300, parfitli, "completely, thoroughly, wholly;" see perfect (adj.) + -ly (2). Meaning "flawlessly, in perfect form or manner" is from late 14c.

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Definitions of perfectly from WordNet

perfectly (adv.)
completely and without qualification; used informally as intensifiers;
you're perfectly right
a perfectly idiotic idea
Synonyms: absolutely / utterly / dead
perfectly (adv.)
in a perfect or faultless way;
She performed perfectly on the balance beam
solved the problem perfectly
spoke English perfectly