1The number ten (10); the last single-digit number and the base unit of the decimal system. Main readings are the Sino-Japanese じゅう and the native-Japanese とお / と. とお is used when counting 1–10 aloud ('hi-fu-mi-yo-itsu-mu-nana-ya-kokono-tō'); と appears in compounds like 十日 (とおか, 'tenth day') and 十路 (とじ, 'in one's tens'). The variant 拾 is used in legal documents to prevent forgery, and the forms 什 and 一〇 also appear in some texts.
じゃあ、明日の朝十時に駅で会いましょう。
Then let's meet at the station at ten tomorrow morning.
彼女は十人の中で一番背が高い。
She's the tallest of the ten of them.
次のテストは十日（とおか）後に行われます。
The next test will be in ten days (tōka).
祖母は「ひい、ふう、みい…」と十まで昔ながらの数え方を教えてくれた。
Grandmother taught me the traditional counting from one to ten: 'hii, fuu, mii … tō.'
領収書には「金拾万円」と書かれていた。
The receipt was written 金拾万円 (one hundred thousand yen) using the legal form of 'ten'.
2The age of ten — an old or literary usage indicating that a person was around ten years old. In modern Japanese this is normally written 十歳 (じゅっさい/じっさい); using 十 alone for this meaning is largely confined to classical or biographical writing.
十にして父を失い、母の手で育てられた。
At the age of ten he lost his father, and was raised by his mother's hand.
3(archaic) A collection or volume of poems — used in classical literary contexts to refer to an anthology of waka or Chinese verse. This usage is essentially extinct in modern Japanese.