noun which may take the genitive case particle 'no'
undeveloped; underdeveloped; not yet developed
Describes something that has not yet reached full development, often used for skills, systems, regions, or organisms.
This area has an underdeveloped transportation network.
His language skills are still undeveloped.
Compound of 未 (mi, 'not yet') + 発達 (hattatsu, 'development'). The reading みはったつ follows standard on'yomi.