IPA: /ˈrɛərli/
KK: /ˈrɛrli/
Not often; occurring infrequently or in small amounts.
She rarely goes to the movies because she prefers reading.
Rarely → It is formed from "rare" (from Latin *rarus*, meaning uncommon or infrequent) and the suffix "-ly" (meaning in a manner of). The word "rarely" means in a manner that is uncommon or infrequently occurring.
Think of something that is 'uncommon' ('rare') happening 'in a manner' ('-ly') — that's why we say rarely.