godan verb (-tsu), intransitive verb
stand on tiptoes
Describes the action of raising oneself onto the balls of the feet.
彼はつま先立って棚の上の本を取った。
He stood on tiptoes and took the book from the shelf.
Alternate kanji spelling using 爪 for つま.
背伸び means stretching oneself upward, often by standing on tiptoes, but can also refer to overreaching or acting beyond one's ability. つま先立つ specifically means standing on tiptoes.
Compound of つま先 (toe tips) and 立つ (to stand).