100 entries under observant topic. ×

5
sensitive(adjective, understanding, open, keen, sharp)
4
all ears(expression, adjective, sharp, bright, lively)
4
hearkening(adjective, attentive)
4
informed(adjective, understanding, keen, sensible, certain)
4
percipient(adjective, understanding, keen, sharp, sensible)
4
sentient(adjective, understanding, open, keen, sensible)
3
savvy(adjective, understanding, keen, sharp, smart)
3
unsleeping(adjective, keen, careful, restless, cautious)
3
with it(expression, adjective, understanding, keen, sharp)
2
acquainted(adjective, understanding, keen, sensible, certain)
2
apprised(adjective, understanding, keen, sensible, certain)
2
au courant(expression, adjective, understanding, keen, sensible)
2
conversant(adjective, understanding, keen, sensible, certain)
2
focused(adjective, feature, characteristic, detail, fixed)
2
on the watch(expression, adjective, idiom, adverb, attention)
2
on to(expression, adjective, understanding, keen, sensible)
2
penetrating(adjective, understanding, strong, sharp, smart)
2
tuned in(expression, understanding, keen, sharp, smart)
2
understanding(adjective, keen, sharp, smart, bright)
2
wise to(expression, understanding, keen, sharp, sensible)
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APASmart Define. (2016). alert thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/alert/thesaurus/synonyms
ChicagoSmart Define. 2016. "alert thesaurus" https://smartdefine.org/alert/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2016, alert thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/alert/thesaurus/synonyms>.
MLASmart Define. "alert thesaurus" 26 February 2016. Web. 27 September 2026. <https://smartdefine.org/alert/thesaurus/synonyms>