This is the 6745th most frequent Russian word.
spider
Spider: An eight-legged arachnid that spins webs to catch prey.
This sentence uses the word 'паук' ('spider') as the subject of an action, illustrating a characteristic behavior associated with spiders.
Паук сплёл паутину.
The spider wove a web.
Here, 'паука' ('spider') is in the accusative case as it is the direct object of the action 'увидел' ('saw').
Я увидел большого паука на балконе.
I saw a big spider on the balcony.
In this case, 'паук' ('spider') is used as a subject in a sentence defining its biological classification.