early 15c., "accusation," from Late Latin detectionem (nominative detectio) "an uncovering, a revealing," noun of action from past-participle stem of detegere "uncover, expose," figuratively "discover, reveal, disclose," from de "un-, off" (see de-) + tegere "to cover," from PIE root *(s)teg- "to cover." From 1610s as "discovery, finding by search or observation," especially "act of finding out and bringing to light."
early 14c., concelen, "to keep close or secret, forbear to divulge," from Old French conceler "to hide, conceal, dissimulate," from Latin concelare "to hide," from con-, here perhaps an intensive prefix (see con-), + celare "to hide" (from PIE root *kel- (1) "to cover, conceal, save"). From early 15c. as "to hide or shield from observation." Replaced Old English deagan. Related: Concealed; concealing; concealable.
1590s, "a private or personal matter, a secret;" c. 1600 as "seclusion, state of being in retirement from company or the knowledge and observation of others," from private (adj.) + abstract noun suffix -cy. Meaning "state of freedom from intrusion or interference" is from 1814. Earlier was privatie (late 14c. as "secret, mystery;" c. 1400 as "a secret, secret deed; solitude, privacy"), from Old French privauté.
1680s, "aware of one's action or oneself," a word of the English Enlightenment (Locke was using it by 1690, along with self-consciousness "state of being aware of oneself, consciousness of one's own identity"), from self- + conscious. The morbid sense of "preoccupied with one's own personality, conscious of oneself as an object of observation to others" is attested by 1834 (J.S. Mill). Related: Self-consciously.
c. 1400, "having a sharp point; producing punctures," senses now rare or obsolete, from Medieval Latin punctualis, from Latin punctus "a pricking" (from nasalized form of PIE root *peuk- "to prick").
The meaning "prompt" is recorded by 1670s, from the notion of "exact, precise, insisting on fine points," including the observation of time and the keeping of appointments (c. 1600). Related: Punctually.