1
general::
Phrase(s): dash something off
to make or do something quickly. • I will dash this off now and try to take more time with the rest of them. • I will see if I can dash off a cherry pie before dinner., Phrase(s): dash off
Go to dash away.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
1. Write or sketch hastily, as in I'm just going to dash off a letter. [Early 1700s] 2. Hurry away, depart hastily, as in He dashed off as though he was being chased. This usage employs the verb dash in the sense of "impetuously run" or "rush," a usage dating from about 1300.
American Heritage Idioms