prefix
Productive prefix meaning 'anti-', 'opposite', or 'counter-'. Attaches to nouns to form compounds like 反対 (opposition), 反応 (reaction), 反論 (objection).
彼は反戦運動に参加した。
He joined the anti-war movement.
その提案には反対意見が多かった。
There were many opposing opinions to the proposal.
noun
Rare standalone noun use, mainly in philosophical or logical contexts. More commonly seen in the compound 反定立 (antithesis).
See also: 反定立
弁証法では、正と反から合が生まれる。
In dialectics, synthesis arises from thesis and antithesis.
noun
fanqie (traditional Chinese spelling system)
Abbreviation of 反切. A technical term in Chinese phonology; rarely encountered outside academic contexts.
See also: 反切
「東」の反は「徳紅切」とされる。
The fanqie for 東 is given as 徳紅切.
非 is a prefix meaning 'non-' or 'un-', indicating negation or lack of something (e.g., 非公式, unofficial), whereas 反 implies active opposition or counter-action.
From Middle Chinese 反 (pjonX). The prefix sense developed from the meaning 'to turn over, to oppose'.