noun
retching; dry heaving
Medical term for the act of trying to vomit without bringing anything up. The English gloss 'vomiturition' is a rare technical synonym.
食中毒の症状として、空嘔が続いた。
As a symptom of food poisoning, retching continued.
つわりで朝から空嘔がひどい。
Morning sickness has caused severe dry heaving since morning.
嘔吐 is the general term for vomiting, while 空嘔 specifically refers to retching without actual vomit.
吐き気 is the sensation of nausea, whereas 空嘔 is the physical act of retching.
Compound of 空 (から, 'empty') and 嘔 (えずき, 'retching'). The reading えずき is a native Japanese term for retching, and 空 indicates the absence of vomit.