无须
wú xū · HSK 7
need not
无须 = 无 (without) + 须 (must/need) = without-must = need not
无 means without or lacking; 须 means must or be required. Stacked together they cancel obligation: there is no must, so you need not and are not obliged to.
无 — top 一 + 林-like middle + fire radical 灬 below
Originally a pictograph of a person dancing while holding ornaments or tassels, meaning 'to dance' — the ancestor of 舞. It was borrowed phonetically to write the negative 'not have / without,' and the dance meaning was reassigned to 舞 with an added foot element. The simplified form 无 comes from an ancient variant.
须 — 彡 (hair strokes) + 頁 (head)
Originally a pictograph showing hair (彡) on a head (頁), depicting a beard or whiskers on a face. The original 'beard' meaning was later written as 鬚, while 须 was borrowed for the abstract sense 'must, need, require.' This phonetic loan usage is now the dominant meaning.