godan verb (-ru), intransitive verb
join a group; mix with people
Rare intransitive verb meaning to enter and mingle with a group of people. Often used in literary or formal contexts.
彼は群衆の中に立ち交じった。
He mingled with the crowd.
Standard kanji spelling.
Variant kanji spelling.
Search-only form; not a standard spelling.
混じる is a more common verb meaning 'to be mixed' or 'to mingle', while 立ち交じる specifically implies standing and joining a group.
Compound of 立ち (tachi, continuative form of 立つ 'to stand') and 交じる (majiru, 'to mingle'). The exact historical derivation is uncertain, but the combination suggests the action of standing among others.