na-adjective
better; preferable; less bad
Used when comparing options, implying that something is not ideal but is better than the alternative. Often used in the pattern ～よりマシ or ～だけマシ.
何もしないよりはマシだ。
It's better than doing nothing.
この店のラーメンはまずいけど、あの店よりはマシ。
The ramen here is bad, but it's better than the one at that shop.
noun, used as a suffix
Attaches to nouns to indicate an increased amount or degree. Common in compounds like 一人増し (one more person) or 倍増し (double the amount).
料金は一人増しで千円高くなる。
The fee increases by 1,000 yen per additional person.
noun
Archaic noun meaning increase or growth. Not used in modern Japanese outside of historical contexts or set phrases.
古文書には「人口の増し」という表現が見られる。
In old documents, the expression '人口の増し' (increase in population) can be found.
Derived from the verb 増す (ます, 'to increase'). The adjectival noun sense developed from the idea of 'increased' → 'better than before/others'.