also: ねんし
That kind of work is impossible for a child who is not yet of age.
He is mature for his age.
歳 is a counter for age, used in phrases like 10歳 (ten years old). 年端 is a noun meaning 'age' itself.
Standard kanji spelling for the common reading としは.
Alternate kanji spelling; also read ねんし, but としは is more common.
Rare reading restricted to this kanji form; としは is the usual reading.
Compound of 年 (とし, 'year') and 端 (は, 'edge, beginning'), literally 'the edge of years', implying the early stage of life or age. The kanji 歯 is an ateji substitution.