celebrate

As a verb celebrate

is to extol or honour in a solemn manner.

As a noun unbirthday is

a day that is not one's birthday but is celebrated as though it were.

As verbs the difference between celebrate and merrymake

is that celebrate is to extol or honour in a solemn manner while merrymake is (archaic|literary) to make merry, have fun, celebrate.

As a noun merrymake is

(archaic|literary) merry-making, celebration, festivity.

As verbs the difference between celebrate and concelebrate

is that celebrate is to extol or honour in a solemn manner while concelebrate is to celebrate along with others.

As a verb celebrate

is to extol or honour in a solemn manner.

As an adjective uncelebrated is

not celebrated; ignored.