noun
paying back in installments; amortization
Original meaning: repayment of a debt in small, gradual installments. Now somewhat dated; the extended sense (sense 2) is far more common.
借金をなし崩しで返す約束をした。
We agreed to pay back the debt in installments.
noun
gradual progression; doing little by little; drifting into a state
Most common modern use. Describes a process that advances step by step, often without a clear plan, and frequently leading to an undesirable or unintended situation. Often used adverbially as なし崩し的に or なし崩しに. Sense 3 (colloquial) adds a nuance of vagueness or quiet fading, but the core idea is the same gradual, unstructured progression.
計画がなし崩し的に延期されていった。
The plan was gradually postponed, bit by bit.
なし崩しに仕事を引き受けてしまった。
I ended up taking on the work little by little without really deciding to.