Onomatopoeia for a diaphragm spasm (3)
I believe the answer is:
hic
(Other definitions for hic that I've seen before include "here in Rome" , "In Latin, here and now - ? et nunc" , "Noise of involuntary diaphragh spasm" , "Sound of involuntary diaphragm contraction" , "Sound of inebriation" .)