1. happy birthday - Verb
2. happy birthday - Interjection
happy birthday
Said or written to a person who is celebrating his or her birthday in order to convey the good wishes of the speaker or writer (literally, "may you have a happy birthday")
Happy birthday, Joe! Have a fantastic day!
Synonyms: many happy returns, many happy returns of the day
happy birthday (third-person singular simple present happy birthdays, present participle happy birthdaying, simple past and past participle happy birthdayed)
(colloquial, transitive) To wish (someone) a happy birthday.
(Can we add an example for this sense?)
After throwing his fifth interception, which was returned for a touchdown, 40,000 or so Cowboys fans at Texas Stadium sang “Happy Birthday to you” to Theismann and he could do nothing but sit on the bench and shake his head. Source: Internet
After sharing the picture on social media, one of said: "Happy birthday! Source: Internet
Athiya posted a super cute photo with the birthday boy, KL Rahul, on social media and captioned the picture as "Happy birthday, my person" with heart emojis. Source: Internet
At 9am on 21st April let’s all sing her Happy Birthday from our windows, balconies and doorsteps and show her how much we care pic. Source: Internet
For example, singing "Happy Birthday" or other relatively common, repeated linguistic discourses, could be fluid in people who stutter. Source: Internet
Fausat Balogun on her Instagram wrote: “Happy birthday to you my beautiful sister, long life with good health, wealth and happiness In sha Allahu. Source: Internet