欠陥【けっかん】
defect, fault, flaw, deformity, deficiency, shortage, gap
陥落【かんらく】
subsidence, sinking, cave-in, collapse, falling in, fall (of a city, fortress, etc.), surrender, fall (in position, rank, etc.), demotion, giving in (to someone's persuasion), yielding, being convinced
陥没【かんぼつ】
cave-in, collapse, sinking, depression (e.g. of the skull), subsidence
陥る【おちいる】
to fall into (e.g. a hole), to fall into (chaos, depression, dilemma, illness, etc.), to fall into (a trap, etc.), to fall, to surrender, to capitulate