The source of the present essay is the discussion of genologic and versification character, addressing the problem of functional assessment of sonnet as a literary unit. The analysis encompassed the lyrics by Jan Kochanowski, Mikolaj Sep Szarzynski and Jan Andrzej Morsztyn. The author remarks that the sonnets of Kochanowski in literary history are derived not from the subject matter but from versification that is their only distinctive feature. Also the analysed sonnet by Morsztyn is received through the category of stanza and rhyme pattern. Szarzynski, on the other hand, directly calls his poems by the name of sonnet, thus indicating their genre distinction. This invites the question whether the lack of genre designation in Kochanowski's sonnets could provide a basis for challenging their status. An affiliation to a specific category undoubtedly offers a convention helping with the reception of a poem. According to Maria Grzedzielska, in the case of the sonnet a versification pattern could be the base of the genre. The symmetry presented in the text between the genre and stanza allows us to accept this standpoint. An unconventional association of the sonnet with the situation of the novel as literary genre, illustrated by a chart, proves that the less is the number of distinctive features of a given literary category, the more it belongs to the genre. The author also refers to the conventions of the sonnet and its numerous transformations over the centuries.