Origins
The verb 'reminisce' is a surprisingly recent addition to English, first attested in 1829 as a back-formation from the noun 'reminiscence,' which had been in the language since the sixteenth century. The noun came from Late Latin 'reminīscentia' (remembrance), from the Latin deponent verb 'reminīscī' (to remember, to call to mind, to recollect), composed of 're-' (again) and a stem related to 'mēns' (mind) and 'meminisse' (to remember). The PIE root is *men- (to think), the fundamental cognitive verb of the proto-language.
The back-formation that created 'reminisce' from 'reminiscence' follows a common English pattern. English speakers encounter a noun ending in '-ence' or '-tion' and assume a corresponding verb must exist, then create one by stripping the suffix. 'Edit' was back-formed from 'editor' (1791). 'Donate' from 'donation' (1845). 'Enthuse' from 'enthusiasm' (1827). 'Reminisce' fits this pattern exactly: the Latin verb 'reminīscī' had not been borrowed directly into English, but the need for a verb meaning 'to engage in reminiscence' was felt, and back-formation supplied it.
The PIE root *men- generated the primary memory and thought vocabulary across the Indo-European languages. Through Latin 'mēns' (mind) and 'meminisse' (to remember): 'mental,' 'mention,' 'memento,' 'memoir,' 'memory,' 'memorize,' 'commemorate,' 'comment,' 'remind,' and 'demented.' Through Greek 'mnēmē' (memory) and 'mimnḗiskein' (to remember): 'mnemonic' (a memory aid), 'amnesia' (loss of memory, from 'a-' + 'mnēsis'), and 'amnesty' (a forgetting — officially choosing not to remember past offenses). Through Sanskrit 'manas' (mind): 'mantra' (a thought-instrument). Through the Germanic branch: 'mind' (from Old English 'gemynd,' memory, thought).
Development
The word 'reminisce' carries a distinctive emotional coloring that most of its synonyms lack. 'To remember' is neutral — one can remember pain, facts, or obligations. 'To recall' is similarly neutral, often implying effort. 'To recollect' is slightly formal. But 'to reminisce' almost invariably implies pleasant memory — a warm, indulgent, often social act of revisiting the past. One reminisces about childhood summers, old friendships, former adventures. The word is rarely used for painful or traumatic memories.
This positive connotation is not inherent in the etymology (Latin 'reminīscī' was neutral) but developed in English usage. The back-formation may have contributed: 'reminiscence' was already associated with pleasurable memoirs and nostalgic reflection by the time the verb was coined, and 'reminisce' inherited that warmth.
The word is often used in social contexts — people reminisce together, sharing memories in conversation. This social dimension distinguishes reminiscing from mere remembering: reminiscence is typically performed aloud, in company, as a form of bonding and narrative pleasure. The phrase 'to sit and reminisce' captures the word's character: unhurried, companionable, savoring the past rather than analyzing it.