latent (adj.) Look up latent at Dictionary.com
mid-15c., "concealed, secret," from Latin latentem (nominative latens) "lying hid, concealed, secret, unknown," present participle of latere "lie hidden, lurk, be concealed," from PIE *late-, suffixed form of root *lādh- "to be hidden" (source also of Greek lethe "forgetfulness, oblivion," Old Church Slavonic lajati "to lie in wait for"). Meaning "dormant, undeveloped" is from 1680s, originally in medicine.