this is a measure given by a md in aʙʀᴇᴀsт ultrasound
I believe it is the equivalent of a centimeter. Yes, I have heard the term before, too, although I am not sure of the correct spelling. I have heard it used if reference to the number of centimeters a woman has dilated in preparation for giving birth.
Edit: It is NOT a mispronounciation...this is a term used by OBGYNs.
There is no word like sonometer inʙʀᴇᴀsт ultrasound
Sonometer Or Centimeter
It is a mispronunciation of "centimeter". It is just under half an inch.
(I HATE when people say it that way!)