1. appear suddenly; "Spring popped up everywhere in the valley"
(synonym) burst out
2. come forth or out; "You stick the coins in, but they come out again"; "His hair and teeth fell out"
(synonym) come out, fall out
(hypernym) issue, emerge, come out, come forth, go forth, egress
3. bulge outward; "His eyes popped"
(synonym) protrude, pop, bulge, bulge out, bug out, come out
(hypernym) change shape, change form, deform
4. exit briefly; "He popped out for a quick coffee break"
(antonym) pop in
(hypernym) exit, go out, get out, leave