Origins
The word 'suspect' entered English around 1300 from Anglo-French 'suspecter,' ultimately from Latin 'suspectus,' the past participle of 'suspicere.' The Latin verb is a compound of 'sub-' (from below, up from under) and 'specere' (to look at, to observe), from the Proto-Indo-European root *speḱ- (to observe). The literal meaning — to look at someone from below — underwent a remarkable semantic transformation: looking up at someone from underneath implied covert observation, wariness, and distrust.
This semantic development has parallels in other languages. The idea that looking at someone from a concealed or inferior position implies suspicion captures something psychologically real about the dynamics of distrust. The person who suspects watches from below — furtively, without the confidence of direct confrontation. Latin also used 'suspicere' in its literal sense of 'to look up at' (with admiration), but it was the darker sense that prevailed in the Romance languages and in English.
Like 'project' and 'subject,' 'suspect' is a heteronym in English. As a verb, the stress falls on the second syllable (/səˈspɛkt/): 'I suspect he's lying.' As a noun or adjective, the stress shifts to the first syllable (/ˈsʌs.pɛkt/): 'He's the prime suspect' or 'The evidence is suspect.' This stress alternation between verb and noun/adjective forms is a hallmark of Latin-derived English vocabulary.
Development
The legal usage of 'suspect' as a noun — a person believed to have committed a crime — is fundamental to the vocabulary of criminal justice. The distinction between a 'suspect' (someone under suspicion but not charged), a 'defendant' (someone formally charged), and a 'convict' (someone found guilty) reflects important legal principles about presumption of innocence. The Miranda warning in American law, which must be read to suspects upon arrest, has made the phrase 'the suspect' one of the most frequently heard legal terms in popular culture.
The related noun 'suspicion' came into English by a slightly different route: from Anglo-French 'suspeciun,' from Late Latin 'suspīciōnem.' The French descendant of this word, 'soupçon,' underwent dramatic sound changes that disguise its Latin origin. In French, 'soupçon' means both 'suspicion' and, in culinary and figurative usage, 'a tiny amount' — just enough to arouse suspicion of its presence. English has borrowed this French sense directly: 'a soupçon of garlic' means a hint, a barely detectable amount.
The adjective 'suspicious' (from Latin 'suspīciōsus') carries two distinct senses that occasionally create ambiguity: 'feeling suspicion' (a suspicious person = someone who suspects others) and 'arousing suspicion' (a suspicious package = something that makes others suspect danger). Context usually disambiguates, but the double meaning reflects the two sides of the suspicion relationship — the watcher and the watched.
Later History
In philosophy, suspicion has been elevated to a methodological principle. Paul Ricoeur coined the phrase 'hermeneutics of suspicion' to describe the interpretive approach of Marx, Nietzsche, and Freud — thinkers who systematically looked beneath the surface of human claims to find hidden motives of class interest, will to power, or unconscious desire. To read with suspicion, in this philosophical sense, is to assume that apparent meanings conceal deeper, less flattering truths.
The word's membership in the 'specere' family connects it etymologically to a remarkable range of English words. The same root that gives us 'suspect' (look from below) also gives us 'inspect' (look into), 'expect' (look out for), 'respect' (look back at), 'prospect' (look forward), 'aspect' (a way of looking), 'spectacle' (something looked at), 'spectrum' (an appearance), and 'speculate' (to observe carefully). Together, these words form one of the most coherent and illuminating root families in English.