Definition of start in
chiefly US, informal
: to start doing a particular activity or action He took a break from painting to eat lunch, then started in again.
Word by Word Definitions
: to move suddenly and violently : spring
: to react with a sudden brief involuntary movement
: to issue with sudden force
: a sudden involuntary bodily movement or reaction
: a brief and sudden action or movement
: a sudden capricious impulse or outburst
Seen and Heard
What made you want to look up start in? Please tell us where you read or heard it (including the quote, if possible).