Clean  —adj. 1 free from dirt or impurities, unsoiled. 2 clear; unused; pristine (clean air; clean page). 3 not obscene or indecent. 4 attentive to personal hygiene and cleanliness. 5 complete, clear-cut. 6 showing no record of crime, disease, etc. 7 fair (a clean fight). 8 streamlined; well-formed. 9 adroit, skilful. 10 (of a nuclear weapon) producing relatively little fallout. —adv. 1 completely, outright, simply. 2 in a clean manner. —v. Make or become clean. —n. Act or process of cleaning.  clean out 1 clean thoroughly. 2 slang empty or deprive (esp. Of money). Clean up 1 a clear away (a mess). B (also absol.) Put (things) tidy. C make (oneself) clean. 2 restore order or morality to. 3 slang acquire as or make a profit. Come clean colloq. Confess fully. Make a clean breast of see *breast. [old english]