noun, suffix
week-old; age in weeks
Used as a noun meaning 'age measured in weeks', or as a suffix attached to a number to indicate the age of a young animal or infant in weeks. Common in veterinary, pediatric, and developmental contexts.
この子犬はまだ週齢3週間です。
This puppy is only 3 weeks old.
週齢別の発達段階を確認する。
Check the developmental stages by week of age.
Compound of 週 (shū, 'week') + 齢 (rei, 'age'). A straightforward Sino-Japanese term.