to fix or attach (something)

attach or stick

to add something in writing; to add something at the end

add, join

to fasten or join (something) (to another)

join, fasten

(to cause an income, group etc) to become larger or better

make greater; improve

(to cause things) to join together

connect, integrate

(to cause things) to become united as one (physical) thing

combine, link

(to cause things) to become (more) solid or strong

combine; make firm

a place where two or more things have been joined together; to come together

unite