1560s, "sealing with a sign," from consign + -ment. Meaning "delivering over" is from 1660s; especially of goods, for the sake of sale or auction, from c.1700. Meaning "quantity of goods so assigned" is recorded from 1720s.
Turning over goods for an agent to sell, with the provision that payment is made only on completed sales and that unsold goods may be returned to the consignor. For example, This secondhand shop accepts items of clothing on consignment.
[ c. 1700