Synonyms for Slow:

adj.

behind, late (adjective)
off, lingering, prolonged, dull, tedious, down, belated, delayed, overdue, tame.
dim (adjective)
Weak-minded.
dull (adjective)
drowsy, comatose, besotted, loutish, lethargic, dim, boorish, thick-witted, bovine, blunt, doltish, soporific, ponderous, apathetic, dull, sluggish, benumbed, dense, cloddish, stupefied, obtuse, sleepy.
gradual (adjective)
gradual.
late (adjective)
belated, tardy.
leisurely (adjective)
unhurried.
lethargic (adjective)
listless, torpid, unhurried, slothful, indolent, insensible, lumpish, drooping, leaden, leisurely, lackadaisical, apathetic, tired, lazy, sluggish, drugged, lethargic, dopey, benumbed, phlegmatic, lifeless, dull, languorous, languid.
oafish (adjective)
lumpish.
procrastinating (adjective)
dilatory.
slow (adjective)
dawdling, Loitering, dragging, sluggish, poky, phlegmatic, crawling, Delaying, Trudging, creeping, plodding, lethargic, leisurely, lingering, slowpoke.
thick (adjective)
slow-witted.
unhurried, lazy (adjective)
measured, Delaying, easy, phlegmatic, dawdling, imperceptible, plodding, sluggish, leaden, crawling, laggard, listless, dreamy, remiss, moderate, apathetic, gradual, quiet, creeping, supine, slack, inactive, indolent, deliberate, negligent, ponderous, Loitering, lackadaisical, dilatory, stagnant, sleepy, passive, leisurely, tardy, lethargic, slothful, drowsy, idle, slow-moving, torpid.
unintelligent (adjective)
dumb, dense, simple, dim, obtuse.

adv.

all (adverb)
easy, behind, tardily, slowly.

n.

trivial, stolid, uninspired, tame, unexciting. darkroom, digicam, slow-footed, aperture, camera, cartridge, celluloid, camcorder, Asa, slow-going, boom, developer. silly, simple, Weak-minded, ability, slow-witted, Feeble-minded, idiotic, half-witted, simple-minded. reduce, behind time, trim down, cut back, halve, lower, minimize, erode, time, top-slice, decrease, shrivel. coffee maker, burner, cooker, broiler, coffee machine, blender, barbecue, beater, colander, Barbie. ease off, brake, throttle back, grind to a halt. sedate, measured, steady, stately. slow (noun)
largo, bumper-to-bumper, slack, larghetto, tiresome, lazy, long-playing, lentissimo, dim, ho-hum, boring, slow up, pokey, tedious, obtuse, larghissimo, easy, inactive, decelerate, dilatory, slow-moving, long-play, Irksome, sluggish, laggard, dumb, behind, tardily, uninteresting, lento, wearisome, drawn-out, drawling, andante, dull, dawdling, deadening, dense, adagio, poky, slacken, slow down, crawling, dragging, slowly, moderato.

v.

delay, restrict (verb)
decrease, ease off, slacken, brake, loiter, reduce, decelerate, cut back, hinder.
slow (verb)
hinder, trudge, plod, crawl, delay, drag, hesitant, dawdle, loiter, poke, creep, linger.

Other synonyms:

slow-witted, stagnant, idiotic, measured, slow-footed, latent, impassable, throttle back, slow-going, slow-paced, dormant. ease off, stately, simple-minded, arterial, sedate, Feeble-minded, half-witted. deliberate, two-way, silly, brake, one-way, Weak-minded, feeder. down, simple. off, tight, steady. decrease
slacken.
irksome
Irksome.
moderate
ease off.
slow down
decelerate.
Other relevant words:
behind, easy, inactive, overdue, slow-witted, stolid, slack, slowly, laggard, behind time, pokey, moderate, gradual, tardy, deliberate, slow up, slacken, belated, ease off, slow down.

Usage examples for slow

  1. He got up, and even made one slow step towards the door; but he did not go out, nor did he seem afraid of me. – A Witch of the Hills, v. 1-2 by Florence Warden
  2. But he'll be slow to part wi' other things, too. – Between You and Me by Sir Harry Lauder
  3. You'll find it rather- rather slow at the school, won't you? – The Varmint by Owen Johnson F. R. Gruger