This thesis studies verb and noun neologisms originating in communication on the Facebook social network and the tool for instant messaging Facebook messenger. The first part of the thesis has introduced neologisms in Croatian language in general, as well as the role and relation between written and spoken language in word formation in Croatian. This part has also presented the theoretical basis for the description of English loanwords adaptation into standard Croatian language. In the second part of the thesis, the corpus of collected verbs and nouns has been analysed according to the origin of the basis and word formation process of each neologism. The examples have been sorted into newly coined words in Croatian language, semantic loanwords and loanwords from the English language or Anglicisms. Anglicisms have further been analysed in terms of adaptation into standard Croatian language on four levels: phonology, morphology, orthography and meaning. The aim of this thesis has been to determine the most frequent word formation processes that occur on Facebook and the way new words adapt into standard Croatian language. The development and increasing frequency of social network usage resulted in a whole new lexical layer which is growing rapidly.