IPA: /ɪnˈtɛnsər/
KK: /ɪnˈtɛnsər/
Having a greater degree of strength, force, or concentration than something else.
The colors in the painting became even intenser as the sun set.
Intenser → It is formed from "intens" (from Latin "intensus", meaning stretched or strained) and "-er" (meaning one who or that which). The word "intenser" refers to something that is more intense or has a greater degree of intensity.
Think of something that is 'stretched' or 'strained' ('intens') to a greater degree — that's why 'intenser' means more intense.