The object of the sentence is

the main noun performing the action
the action of the sentence; what is being done
the noun or pronoun the action is done to
an auxiliary word

Traditional grammar defines the object in a sentence as the entity that is acted upon by the subject. There is thus a primary distinction between subjects and objects that is understood in terms of the action expressed by the verb, e.g. Tom studies grammar—Tom is the subject and grammar is the object

so the answer is object is the noun that the action is done to

(wikipedia defenition)