zīdainis

From zīst (past stem: zīd-) (“to suck, to suckle”) +‎ -ains, made into a masculine 2nd-declension noun (ending -is).

zīdainis m (2nd declension, feminine form: zīdaine)

1. infant, baby (child in its first year of life, when its basic food is mother's milk)

   zīdaiņa kopšana ― baby care

   zīdaiņa uzturs ― baby nutrition, diet

   zīdaiņa vecums ― infancy (lit. baby age)

2. (colloquial) naive person

   Edžus apsaukā mani par zīdaini: “zīdaini, cik ir divreiz divi?” ― Edžus called me a baby: “baby, how much is two times two?”

The feminine form zīdaine is attested but rather rare.

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