infantile

What it means

1. Pertaining to infants.

   infantile paralysis

   2 more examples

   They and the old North London tanks at Richmond long ago were the first engines on which my infantile eyes rested, be it said with an admiration that the years have never dimmed.

   1957 February 28, Henry Maxwell, “A Sentimental Journey”, in Railway Magazine, page 82

   Eustace gaped at him in amazement. When his urbanity dropped away from him, as now, he had an innocence of expression which was almost infantile. It was as if the world had never touched him at all.

   1963, Margery Allingham, chapter 9, in The China Governess: A Mystery, London: Chatto & Windus, →OCLC

2. Childish; immature.

   Synonyms: juvenile, puerile, babish, babyish, bairnish, childish, dootsie, hissy

In a sentence

infantile paralysis

Where it comes from

1. Latininfantilis“pertaining to an infant”
2. Englishinfantile

Mid-15th century, "pertaining to infants," from Latin infantilis (“pertaining to an infant”), equivalent to infant + -ile, from īnfāns. Sense of "infant-like" is from 1772.