immaturity

 
Pronunciation: /ˌɪməˈtʃɔːrɪti, ˌɪməˈtʃʊərɪti, ˌɪməˈtjɔːrɪti, ˌɪməˈtjʊərɪti/

noun

[mass noun]
  • the state of being immature or not fully grown: the immaturity of the immune system in very young children makes them especially vulnerable
  • behaviour that is appropriate to someone younger: they were shocked by such immaturity in a grown man