birthday

As a noun birthday

is the anniversary of the day on which someone is born.

As an adjective undefined is

lacking a definition or value.

As nouns the difference between birthday and boyfriend

is that birthday is the anniversary of the day on which someone is born while boyfriend is a male partner in a romantic relationship.

As nouns the difference between birthday and brother

is that birthday is the anniversary of the day on which someone is born while brother is title of respect for an adult male member of a religious or fraternal order.

As nouns the difference between birthday and birthdays

is that birthday is the anniversary of the day on which someone is born while birthdays is .

As nouns the difference between daylight and birthday

is that daylight is the light from the sun, as opposed to that from any other source while birthday is the anniversary of the day on which someone is born.

As a verb daylight

is to expose to daylight.

As a verb whelped

is (whelp).

As a noun birthday is

the anniversary of the day on which someone is born.

As nouns the difference between daytime and birthday

is that daytime is the time of daylight; the time between sunrise and sunset while birthday is the anniversary of the day on which someone is born.

As an adjective daytime

is pertaining to daytime; appropriate to the day.