Quick answer
The populace is a noun — the general population of a place. Populous is an adjective meaning having many inhabitants. So a populous city has a large populace. One names the people; the other describes how many there are.
The core difference
A noun and an adjective from the same root.
- populace (noun) — the population: the local populace.
- populous (adjective) — densely inhabited: the most populous state.
The endings tell you
-ace here forms a noun, as in furnace and surface. -ous forms an adjective, as in famous, dangerous, nervous. That suffix pattern is reliable across English and settles this pair instantly.
The tone of populace
Populace sometimes carries a faintly distancing tone, suggesting the ordinary mass of people as viewed from outside. Population is the neutral word if that implication is unwanted.
Frequently asked questions
Which one is the adjective?
Populous — densely inhabited. Populace is the noun.
How do I remember it?
The -ous ending marks adjectives, as in famous and dangerous. The -ace ending marks a noun.
Is populace neutral?
It can carry a faintly distancing tone. Population is the neutral alternative.
