Polish, a Western Slavic language, belongs to the group of inflected languages by virtue of its structure. Like other languages in this group, when a new word is derived in Polish, the roots of the word sometimes change completely and become unrecognizable, while at other times the actual letters in the stem remain the same in the new word. At other times there is only a bond between the root and the new word. Words can be preceded, centered, or ended by the affix. Lexicalization implies the appearance of the need to establish new semantics that has not existed in the language before, and the creation of new words triggered by this need. One of the most effective methods of word derivation in Polish is the addition of affixes to existing roots. However, it is also seen that the required concept cannot always be expressed by means of the root and affixes. In such cases, it is possible to follow the methods of forming a compound word, borrowing words from other languages or generating and forming a new word in order to create a new concept. This study aims to examine the word structure of Polish, and the methods used in word derivation, cognate words, prefixed and non-prefixed words. It tries to identify the letter changes that occur in word derivation. It shows the methods for determining the roots of verbs, and analyzes how meaning can be derived from them. It deals with the issue of whether a derivational affix adds the same meaning to each word and emphasizes the place and importance of auxiliary words in language in word derivation. In addition, it examines the tasks and characteristics of auxiliary verbs.