From Longman Dictionary of Contemporary Englishdash off phrasal verb1 LEAVE A PLACEto leave somewhere very quickly Harry dashed off before she had a chance to thank him.2 dash something ↔ offWRITE to write or draw something very quickly She dashed off a quick letter. → dash→ See Verb table
Examples from the Corpus
dash off• He was furious when he saw the article, and dashed off a letter to the editor immediately.• The publishers wanted a summary that afternoon, so I dashed it off in an hour or so. 