Synonyms for On the lookout:

• adj.

  •alert (adjective)
  • clever,
  • with it,
  • heedful,
  • bright,
  • sharp,
  • wired,
  • watchful,
  • perceptive,
  • wise,
  • intelligent,
  • spirited,
  • active,
  • cagey,
  • hip,
  • ready,
  • careful,
  • circumspect.
  •attentive (adjective)
  • awake,
  • fascinated,
  • hooked,
  • Enrapt,
  • enthralled,
  • glued,
  • studious,
  • mindful,
  • interested,
  • regardful,
  • more interested,
  • hanging on every word,
  • preoccupied,
  • Immersed,
  • conscientious,
  • aware,
  • listening,
  • intent.
  •cautious (adjective)
  • SAFER,
  • playing it cool,
  • prudent,
  • forethoughtful,
  • tentative,
  • with one's eyes peeled,
  • chary,
  • taking it easy,
  • discreet,
  • judicious,
  • walking on eggs,
  • taking it slow,
  • calculating,
  • watching out,
  • safest,
  • hedging one's bets,
  • keeping on one's toes,
  • gingerly,
  • thinking twice,
  • watching one's step,
  • leery,
  • provident,
  • playing safe,
  • shrewd,
  • pussyfoot,
  • shrewdest,
  • safe,
  • considerate.
  •guarded (adjective)
  • canny,
  • noncommittal,
  • reticent,
  • restrained,
  • reserved.
  •on one's guard (adjective)
  • upon one's guard.
  •on the ball (adjective)
  • lively.
  •open-eyed (adjective)
  • openeyed.
  •politic (adjective)
  • delicate,
  • smooth,
  • expedient,
  • diplomatic,
  • adroit,
  • sagacious,
  • perspicacious,
  • advisable,
  • sensible,
  • urbane,
  • cool.
  •unsleeping (adjective)
  • un sleeping,
  • un-sleeping.
  •vigilant (adjective)
  • looking for,
  • with weather eye open,
  • watching,
  • acute,
  • on alert,
  • waiting on,
  • looking to,
  • agog,
  • on toes,
  • anxious.
  •wakeful (adjective)
  • Insomnious,
  • waking,
  • astir,
  • insomniac.
  •wary (adjective)
  • sly,
  • saving,
  • frugal,
  • sparing,
  • distrustful,
  • thrifty,
  • suspicious,
  • doubting.
  •wide-awake (adjective)
  • bright-eyed and bushy-tailed,
  • wide-eyed,
  • wideawake.

• adv.

  •on guard (adverb)
  • defensive.

• adv

  •on guard (adverb)
  • on watch.

• Other synonyms:

  •Other relevant words:
  • alive,
  • hawk-eyed,
  • lidless,
  • on the watch,
  • eagle-eyed,
  • keen,
  • keen-eyed,
  • sleepless,
  • open-eyed,
  • watch,
  • aux aguets,
  • attentive to,
  • unsleeping,
  • all eyes,
  • conscious,
  • argus-eyed,
  • sharp-eyed,
  • on the alert.

Antonyms for On the lookout:

• adj.

  • alert
    inattentive, drowsy, careless, unobservant, dull, ignorant, asleep, foolish, thoughtless, lazy, indifferent, stupid, uneducated, unintelligent, lethargic, weary, negligent, unaware, indiscreet, slow, incautious, sluggish.
  • attentive
    heedless, Neglecting, inconsiderate, neglectful, Unattentive, disregarding.
  • cautious
    imprudent, sure, uncareful, reckless, rash, unwise, certain, hasty, unguarded.
  • guarded
    bold, extroverted, unwatchful, unsuspicious, outgoing.
  • politic
    injudicious, impolitic, tactless.
  • vigilant
    impulsive.
  • wakeful
    sleepy.