send in

1. 1.

   mail in; cause to be delivered

   “Send in your comments”

   Broadersend
2. 2.

   give one's name or calling card to a servant when making a formal visit

Questions about send in

What does send in mean?

send in means "mail in; cause to be delivered". That is the primary sense; the word has 2 in total, listed in full on this page.

Is send in a common word?

send in is banded "Uncommon" — turns up in careful writing rather than conversation. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.