"wary" in the adjective sense
marked by keen caution and watchful prudence
"they were wary in their movements"
"a wary glance at the black clouds"
"taught to be wary of strangers"
2. leery, mistrustful, suspicious, untrusting, wary
openly distrustful and unwilling to confide
Source: WordNet® (An amazing lexical database of English)
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