c.1290, from Anglo-Fr.
suspecioun, from O.Fr.
suspeçun, sospeçon "mistrust, suspicion" (Fr.
soupçon), from L.
suspectionem (nom.
suspectio) "mistrust, suspicion, fear, awe," from pp. stem of
suspicere "look up at" (see
suspect). Spelling in Eng. infl. 14c. by learned O.Fr. forms closer to L.
suspicionem.
Suspicious "deserving of or exciting suspicion" is recorded from 1340, from O.Fr.
suspecious, from L.
suspicious "exciting suspicion." Meaning "full of or inclined to feel suspicion" is attested from c.1400. Edgar Allan Poe (c.1845) proposed
suspectful to take one of the two conflicting senses of
suspicious.