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ñoño (Adjective) "silly;" "senile"
First clear attestation dates to the 19th cent. A 15th cent. recording of ñonio is of unclear meaning. From Late Latin nonnus "monk," "elderly person." Reconstructed by de Vaan (2014) as from Proto-Indo-European *nVnV "daddy," "nanny."
Variants
Cuba ñongo "indiscrete," Venezuela ñongo "insecure," "high-maintenance" (< Vulgar Latin *nonicus). Note zero palatalization in Costa Rica, Honduras, Nicaragua noneco "silly," which reflects Vulgar Latin *nonus with suffix -eco, indicating deformity. Also note 12th cent. variant nana "married woman."
Indo-European
Romance
Italian nonno, Romanian nun
Celtic
Welsh nain "grandmother"
Albanian
Albanian nënë "mother"
Balto-Slavic
Russian njánja "child nanny," Bulgarian neni "elder"
Hellenic
Ancient Greek νάννας (nánnas) "uncle," "aunt"
Indo-Iranian
Sanskrit nanā́ "mother"
Double palatalization of Latin n-nn- > Spanish ñ-ñ- is unusual, though not unheard of, and may have been deformed by children's speech. This may reinforce the theory that various *nVn- words in Vulgar Latin are of nursery origin (cf. niño, nene, nona).