to join to something else so as to bring about an increase or improvement
to serve as an addition to something
to join (something to something else) so as to bring about an increase or improvement
Wine adds a creative touch to cooking
to say or write (something) further
She added that she might be late
(often + up) to combine (numbers) into a single number
to add up numbers
The children are learning to add
(+ to) to make or serve as an addition to something
Being robbed just added to his misery
[Middle English adden from Latin addere, from ad- + -dere to put]