Clueless

来自Big Physics

wiktionary

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clue +‎  -less


etymonline

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clueless (adj.)

1817, "trackless," from clue (n.) + -less. Meaning "ignorant, uninformed" is by 1943, said to be RAF slang from 1930s. Student slang use by 1985 is perhaps an independent extension along the same line. Related: Cluelessly; cluelessness.