Here, we call someone who celebrates his birthday a birthday celebrant. For example, there is a party and a relative comes in and asks: Who is the celebrant? Some people will tell him it's Peter's birthday today or simply answer "Peter". However, local English trainers consider this term a Filipinoism. They say that the correct term is celebrator because a celebrant is the officiating priest in a Eucharist or mass. But there is another English trainer who pointed out that the two are actually interchangeable. And it seems that the latter is correct. When I looked up my Merriam-Webster unabridged, it says: b : one who participates in any noisy party (as one at which there is a good deal of drinking) And this is what Wordreference Dictionary says: 2 celebrant, celebrator, celebrater: a person who is celebrating Is it correct to use the word celebrant to refer to those celebrating their birthday? Is it a commonly used term when you attend birthday parties? If not, how would you inform someone that it is somebody's birthday? Even if the term is correct, I don't think it sounds natural to you. Please give expressions used by native speakers. Thank you.