Denshi Jisho — Online Japanese dictionary

落とす おとす 1: to drop; to lose; to let fall; to shed (light); to cast (one's gaze); to pour in (liquid); to leave behind;
2: to clean off (dirt, makeup, paint, etc.); to remove (e.g. stains or facial hair); to lose; to spend money at a certain place; to omit; to leave out; to secretly let escape;
3: to lose (a match); to reject (an applicant); to fail (a course); to defeat (in an election);
4: to lower (e.g. shoulders or voice); to lessen (e.g. production or body weight); to worsen (quality); to reduce (e.g. rank or popularity); to speak badly of; to make light of; to fall into straitened circumstances;
5: to fall into (e.g. a dilemma or sin); to make one's own; to have one's bid accepted; to force surrender; to take (e.g. an enemy camp or castle); to forcefully convince; to press for a confession; to deal with;
6: (Computer terminology) to download; to copy from a computer to another medium;
7: (Martial arts term) to make someone swoon (judo);
8: to finish a story (e.g. with the punch line);
9: to finish (a period, e.g. of fasting)
Common word, Godan verb with su ending, Transitive verb 

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