Definitions for on tap
(of liquids) available by turning a tap
"ale on tap"; "hot and cold running water on tap"
available for immediate use
"extra personnel on tap"; "other sports and entertainment facilities are on tap"; "there are numerous projects on tap"
Available directly from the barrel by way of a tap.
Readily available; ready for use.
On an agenda, planned, expected.
Origin: From tap. Sense 2 recorded from 1483.