1) Accelerate 2) Aggravate 3) Amp 4) Deepen 5) Enhance 6) Escalate 7) Escalte 8) Heat up 9) Heighten 10) Hone 11) Quicken 12) Ramp up 13) Redouble 14) Revup 15) Stepup 1) Add to 2) Amplify 3) Augment 4) Become more acute 5) Become more intense 6) Enhance 7) Enlarge 8) Escalate 9) Grow stronger 10) Improve 11) Increase 12) Magnify 13) Make stronger and deeper 14) Multiply 15) Pick up 16) Reinforce 17) Renew 18) Step up 19) Strengthen 20) To render more intense 21) Worsen 
• (v. t.) To render more intense; as, to intensify heat or cold; to intensify colors; to intensify a photographic negative; to intensify animosity. • (v. i.) To become intense, or more intense; to act with increasing power or energy.
[Verb] To make stronger or greater.
In·ten'si·fy transitive verb [ imperfect & past participle Intensified ; present participle & verbal noun Intensifying .] [ Intense + - fly .] To render more intense; as, to intensify heat or cold; to intensify...
[v] - photography: make the chemically affected part of (a negative) denser or more opaque in order produce a stronger contrast between light and dark 2. [v] - make more intense, stronger, or more marked 3. [v] - become more intense
deepen verb become more intense; `The debate intensified`; `His dislike for raw fish only deepened in Japan`
increase in extent
increase in extent