Antonyms of adj groggy

1 sense of groggy

Sense 1
dazed, foggy, groggy, logy, stuporous -- (stunned or confused and slow to react (as from blows or drunkenness or exhaustion))

INDIRECT (VIA lethargic) -> energetic -- (possessing or exerting or displaying energy; "an energetic fund raiser for the college"; "an energetic group of hikers"; "it caused an energetic chemical reaction")

Similarity of adj groggy

1 sense of groggy

Sense 1
dazed, foggy, groggy, logy, stuporous -- (stunned or confused and slow to react (as from blows or drunkenness or exhaustion))
       => lethargic (vs. energetic), unenrgetic -- (deficient in alertness or activity; "bullfrogs became lethargic with the first cold nights")