wú​duān

for no reason

无端 無端 wú​duān
for no reason
without cause or reason; for no reason at all; pointlessly
endless
without start or end; limitless; infinite
unreasonable
unprincipled; unscrupulous; (literary) malicious or behaving like a rascal
unavoidable
(literary) used to express frustration that something is happening despite one's wishes, meaning 'unavoidably' or 'regrettably'
groundless accusation
a trumped-up charge; a groundless accusation or fabricated case

Frequency

Movie subtitles
1.58 per million appears in 1% of films
Written text
2.90 per million

Sources