IPA: /ˈdɛn.sər/
KK: /ˈdɛn.sɚ/
Having a lot of mass or substance in a small area; thicker or heavier than something else.
The fog was denser in the valley than on the hilltop.
Denser → It is formed from "dense" (from Latin "densus", meaning thick or closely packed) and the comparative suffix "-er" (meaning more). The word "denser" means more thick or closely packed than something else.
Think of something that is 'more thick' or 'more closely packed' — 'dense' describes that quality, and '-er' indicates a comparison.