burst into tears, begin to cry

(intransitive) to cry; to weep; to sob / (transitive) to grieve over something

(colloquial) a girlfriend (a female partner in a romantic relationship)

(literary) they (about women or girls)

(formal) Female third-person singular pronoun; she, her, girlfriend

all of a sudden, all at once

sudden

suddenly

conjunctive form of 泣く (naku) [godan]

to take out, to get out / to put forth; to show or reveal / to submit, to turn in / to publish, to make public / to demonstrate, to show / to send something, like a letter / to begin, give rise to