IPA: /nɒnˈɒptɪməl/
KK: /nɑnˈɑptəməl/
Not the best or most effective option; less than ideal.
The current solution is nonoptimal and needs improvement.
Nonoptimal → It is formed from "non-" (meaning not) and "optimal" (from Latin "optimus", meaning best). The word "nonoptimal" means not the best or less than the best.
Think of 'non-' meaning 'not' and 'optimal' meaning 'best' — so nonoptimal refers to something that is not the best.