IPA: /ˌdɪsprəˈpɔːrʃənl/
KK: /dɪsprəˈpɔrʃənl/
Not in correct or balanced proportion; unequal in size, amount, or degree.
The funding for the project was disproportional to the number of people it would benefit.
Disproportional → It is formed from "dis-" (meaning apart or not) and "proportional" (from Latin "proportio" meaning proportion). The word describes something that is not in proportion or not balanced in relation to something else.
Think of 'not' ('dis-') being related to 'proportion' — this helps you remember that 'disproportional' means something that is out of balance or not in proportion.