Several parts combine into one character.

泣 is a phonetic-semantic compound: 氵 (water) + 立 (lì, "to stand"). 立 provides the sound (the Sino-Japanese reading shifts irregularly), while 氵 carries the meaning — water flowing while one stands = tears flowing while one weeps. 泣 forms a tight pair with 涙 (lèi, tears): 涙 is the noun "tears," 泣 is the verb "to weep" — the substance and the action sharing the same water radical.

Korean reading "eup." Korean keeps 泣 strictly in formal and literary register: 泣訴 (eupso, tearful appeal — used in legal or news contexts for someone weeping while pleading), 感泣 (gameup, tears of gratitude / overwhelmed weeping), 涕泣 (cheeup, sobbing — literary), 哭泣 (gokeup, lamentation). For everyday "to cry," Korean overwhelmingly uses the native (ulda); 읍 appears only in elevated speech.

Mandarin qì, 4th tone. The compound 哭泣 (kūqì) pairs the everyday 哭 (kū, to cry — colloquial) with the literary 泣 — together meaning "to weep / lament." 泣不成声 (qì bù chéng shēng, "to weep so hard one cannot make sound" = utterly broken-hearted), 暗泣 (ànqì, to weep silently / weep in secret). Modern Chinese spoken usage prefers 哭, with 泣 surviving in literary, poetic, and idiomatic contexts.

Japanese on-reading キュウ (kyū) is rare — 感泣 (kankyū, tears of emotion). The kun-reading なく (naku, "to cry") is what matters: 泣く (naku, to weep), 泣き虫 (nakimushi, "crying bug" = crybaby), 泣き顔 (nakigao, tearful face), 泣き寝入り (nakineiri, "to fall asleep crying" = to give up in resignation, often referring to suffering an injustice without recourse). Critical homophone caution: なく is the kun-reading for both 泣く (a person crying) and 鳴く (an animal vocalizing — birds singing, dogs barking, cats meowing, insects chirping). Same kana, different kanji, fundamentally different events. Japanese clearly distinguishes the two with kanji choice.

Memory aid: water (氵) flowing while one stands (立) — tears falling as you remain there.