IPA: /ˈtɛn.sər/
KK: /ˈtɛn.sɚ/
More tense than something else; having a greater degree of tension.
The atmosphere in the room became tenser as the debate continued.
This word originates from Latin 'tensus', meaning stretched or tense. The word 'tenser' refers to something that is more stretched or under greater tension than something else.
Think of something that is 'stretched' or 'under tension' — that's why 'tenser' means more tense.