掌掴 is a verb meaning 'to slap (someone) forcefully with the open palm of the hand.' It combines two characters: 掌 (zhǎng), meaning 'palm of the hand,' and 揣 (guó), an archaic or literary verb meaning 'to strike' or 'to hit sharply.' Together, they form a compound that emphasizes the physical action of striking with the palm — not with fingers clenched (which would be 拳打, 'punching') nor with the back of the hand (which is 扇耳光). The word carries strong emotional connotations, often implying anger, humiliation, punishment, or sudden outrage.

It appears frequently in literature, film scripts, and formal or dramatic speech. While grammatically transitive, it usually requires a direct object (e.g., 掌掴他), and it’s rarely used in casual daily conversation — native speakers more commonly say 打耳光 or just 扇 in informal contexts. Its tone is emphatic and vivid, making it especially effective in descriptive or narrative writing where physical intensity matters.