something that lasts a lifetime; high-quality lifelong item
Colloquial noun, often used for durable goods, tools, or products of exceptional quality that one expects to use for life. The suffix もん is a casual contraction of もの.
See also: 一生もの
This kitchen knife is something that will last a lifetime.
Good furniture becomes a lifelong item, so it's worth buying even if it's a bit expensive.
Katakana variant of the suffix, often used for emphasis or in casual writing.
Compound of 一生 (いっしょう, 'lifetime') and the colloquial suffix もん, a contraction of もの ('thing').