RA
adjective anatomy specialized uk/ɑː ˈeɪ/ us/aːr ˈeɪ/
桡动脉（radial artery的缩写）
abbreviation for radial artery: the artery (= large blood vessel) that goes from below the elbow to the palm of the hand
RA
noun [ C ] anatomy specialized uk/ɑː ˈeɪ/ us/aːr ˈeɪ/
右心房（right atrium的缩写）
abbreviation for right atrium: the right upper chamber (= space) of the heart