The purpose of this paper is to review the work of Mattiello(2023), which expanded the scope of combining forms to treat them as a distinct category and compiled a comprehensive overview of combining forms in English, and to examine the applicability of this framework to Korean. Combining forms were classified into three types in Mattiello(2023): neoclassical combining forms, abbreviated combining forms, and secreted combining forms. Among these, neoclassical combining forms were considered to resemble compounding, whereas abbreviated and secreted combining forms were regarded as resembling derivation. Above all, combining forms were established as an independent category because, although they share characteristics with both derivation and compounding, they were viewed as possessing transitional characteristics that straddle these two processes. To this end, a transitional morphology that includes combining forms was proposed. Neoclassical combining forms were regarded as loan elements that retain more of the characteristics of a root; this can be said to bear many similarities to Sino-Korean in various respects. Abbreviated combining forms and secreted combining forms are also found in recent new words in Korean, and many of the examples examined by Mattiello(2023) are frequently encountered in Korean new words as well. While some of these can be viewed as borrowings, their patterns of combination with Sino-Korean suggest that they function as word-forming elements in Korean as well. I also argued that the possibility of identifying such elements exhibiting transitional properties as a distinct category can also be applied to abbreviators, which function as fixed elements in the formation of term abbreviations. This is because, although abbreviators are not closely related to blending, they exhibit transitional properties in that some are treated as affixes or nouns, while others are treated as both affixes and nouns.