psst
Synonym discussion
Sense: exclamation/1
All three words are used to get someone's attention, but they differ in volume and social context. 'Psst' is a quiet, breathy sound made with the lips almost closed, used when you want to call someone secretly — for example, across a classroom or library. 'Hey' is much louder and more casual, suitable for calling a friend on the street or getting a waiter's attention. 'Ahem' is a throat-clearing sound that signals mild disapproval or draws polite attention to a situation, such as reminding someone they forgot to say thank you. Choose 'psst' when discretion matters, 'hey' for ordinary casual attention-getting, and 'ahem' for polite correction or notice.
Etymology
Imitative — the word is meant to sound like the hissing or breathy noise people make with their lips to attract someone's attention quietly. It first appeared in English writing in the late 1800s as a way to represent this natural sound in dialogue.