Webster's Revised Unabridged Dictionary · 1913

Latchstring

Latchstring , noun

A string for raising the latch of a door by a person outside. It is fastened to the latch and passed through a hole above it in the door.
Collocations (1)
To find the latchstring out , to meet with hospitality; to be welcome. (Intrusion is prevented by drawing in the latchstring.) [Colloquial United States]