Attaches

ADDS ON

Think of how you might extend something by including extra parts, like adding pages to a document or toppings to a pizza.

Attaches" hints at something being joined or connected, which is where "ADDS ON" comes in. The phrase literally means to include or append something extra, fitting the idea of attachment. The wordplay is straightforward—no tricks here—just a direct definition where "adds on" serves as a verb phrase meaning to affix or link.