- heavily (adv.)
- Old English hefiglice "violently, intensely; sorrowfully; sluggishly," from hefig (see heavy) + -ly (2).
- slowly (adv.)
- Old English slawlice "slowly, sluggishly;" see slow (adj.) + -ly (2).
- sluggish (adj.)
- mid-15c., from Middle English slugge "lazy person" (see sluggard) + -ish. Earlier adjective was sluggi (early 13c.). Related: Sluggishly; sluggishness.