noun
suckling infant; nursing baby
Rare term for a baby still being breastfed. More commonly expressed as 乳飲み子 or 哺乳中の赤ちゃん.
哺乳児は母乳から免疫を得る。
A suckling infant acquires immunity from breast milk.
哺乳 means 'lactation' or 'nursing'; 哺乳児 specifically refers to the infant being nursed.
Compound of 哺乳 (ほにゅう, 'nursing, lactation') and 児 (じ, 'child, infant').