noun, na-adjective
thousands; a great many; all sorts of
Literary or formal word for a vast number or great variety. Often used in the adverbial form 千々に (ちぢに) meaning 'in countless ways' or 'into many pieces'. Not used in casual counting.
See also: 千々に
千々の思いが胸をよぎる。
A thousand thoughts cross my mind.
彼の心は千々に乱れた。
His heart was torn in countless directions.
無数 means 'countless' or 'innumerable' and is a more neutral, everyday term compared to the literary 千々.
Reduplication of 千 (ち, 'thousand') with rendaku voicing, yielding ちぢ. The iteration mark 々 is used in the standard spelling 千々.