歳（さい、sai）
- ~years old

The Japanese word 歳 (さい) primarily means "years old" or "age." It's used to specify a person's age or the age of something, similar to how we use "years old" in English. It can also refer to "years" as a unit of time, but its primary function is to express age.

⚫︎私歳は二十歳です。 Translation: I am twenty years old. ⚫︎子供はまだ五歳です。 Translation: The child is still five years old. ⚫︎あの車はもう十歳です。 Translation: That car is already ten years old.

⚫︎When asking someone's age: You can use the question お幾つですか？ (oikutsu desu ka?) which is a polite way to ask "How old are you?" ⚫︎When giving your age: You'll typically say a number followed by 歳. For example, if you are 25, you say 二十五歳 (nijuu go sai). ⚫︎It's important to note the counter word for age is 歳. ⚫︎Be careful with the pronunciation of the numbers, especially when counting age. The pronunciation of the counter 歳 doesn't change based on the number preceding it.

⚫︎The word 歳 is usually written with the kanji 歳. ⚫︎The hiragana reading is さい (sai). ⚫︎There is only one way to write the kanji and it does not change.

⚫︎While there aren't direct synonyms for expressing age, here's a related concept: ⚫︎年齢 (ねんれい - nenrei): This word means "age" in a broader sense and can refer to a person's age or the age of objects, situations, etc. This is useful in contexts where you're not specifically counting "years old" but rather talking about the concept of age.

⚫︎There aren't really antonyms for the word 歳, as it is a specific unit of measure.

彼女は今年で三十歳になります。 ・Translation: She will be thirty years old this year. ・Explanation: This sentence uses 歳 to express the girl's age in the current year.

犬の寿命は人間より短いので、犬の歳を人間の歳に換算する方法があります。 ・Translation: Because the lifespan of dogs is shorter than humans, there is a way to convert dog years into human years. ・Explanation: This sentence demonstrates 歳 being used in a comparative context regarding age.

⚫︎The kanji 歳 is a combination of two parts: ⚫︎The upper part represents a seed or a year. ⚫︎The lower part represents a step or movement. ⚫︎Combined, it suggests the concept of growing or progressing through the years, which is the meaning of "age."