匹（ひき、hiki）
- ~small animals

The word 匹 (ひき) is a counter word in Japanese, primarily used to count small animals. It's used for animals that are relatively small and can be easily handled, unlike larger animals that might use a different counter. The concept is similar to using the word "head" or "piece" for animals in English, but 匹 (ひき) is specifically for smaller creatures.

⚫︎ 犬が二匹います。 Translation: There are two dogs. ⚫︎ 猫が一匹寝ています。 Translation: One cat is sleeping. ⚫︎ 金魚が三匹泳いでいます。 Translation: Three goldfish are swimming.

You use 匹 (ひき) when counting small animals. This includes pets like dogs, cats, fish, insects, and other small creatures. When speaking, the pronunciation of 匹 (ひき) may change depending on the number. For instance, "one" is 一匹 (いっぴき), "three" is 三匹 (さんびき), and "six" is 六匹 (ろっぴき).

The word is typically written as 匹 (ひき) in kanji. The hiragana reading is ひき. There are no other ways to write this word commonly. The okurigana is always "き" (ki). The pronunciation varies depending on the number being counted.

There aren't direct synonyms for 匹 (ひき) in terms of counting units, but other counters are used for other animals. For example, 頭 (とう - head) can be used for larger animals, and 羽 (わ - wings) for birds.

There aren't antonyms for counting units, but there are different counters used based on the type of object being counted.

うちには猫が五匹います。 ・Translation: We have five cats at home. ・Explanation: This sentence uses 匹 (ひき) to count the number of cats the speaker has.

庭にカエルが二匹いた。 ・Translation: There were two frogs in the garden. ・Explanation: This sentence uses 匹 (ひき) to count the number of frogs.

The etymology of 匹 (ひき) is related to the idea of a "pair" or "match". It suggests the notion of one unit, often referring to one animal or a single instance of something.