the.com/mentality

means A characteristic way of thinking, or the particular attitude someone brings to a situation.

from Built from Latin 'mentalis' (of the mind), itself from 'mens' (mind) — the same root that gives us 'mental' and 'mention.' English bolted on the abstract-noun suffix '-ity' to turn 'mental' into a thing you can have, blame, or lack, much like 'reality' or 'sanity.' The word only really caught on in the 19th century, when it picked up its slightly judgmental edge — a 'mentality' is rarely neutral; it's usually someone else's way of thinking, diagnosed from the outside.