This is the 5239th most frequent Japanese word.
飛行機
Airplane.
In this sentence, '飛行機' is used in its generic sense as a common noun to describe the concept of airplanes.
飛行機は空を飛ぶ乗り物です。
Airplanes are vehicles that fly in the sky.
Here, '飛行機' refers to a specific airplane that was observed, making the noun act more specific within the context.
昨日、新しい飛行機を見ました。
Yesterday, I saw a new airplane.
In this instance, '飛行機' is used in relation to the mode of transportation, showing its functional usage as a means of travel.