This is the 5562nd most frequent Japanese word.
きす
"きす" can mean "kiss" or refer to a type of fish called "sillago" (Japanese whiting).
In this sentence, "きす" refers to the act of a kiss (noun form).
彼は彼女にきすをしました。
He kissed her.
Here, "きす" refers to a type of fish, commonly known as sand fish.
海で新鮮なきすを釣りました。
I caught fresh sand fish in the sea.
This sentence again uses "きす" in the context of the fish species when discussing culinary applications.