The current study aims at exploring the grammaticalization of the nouns ʃikil 'shape' and omir 'age' in Jordanian Arabic. The data were collected from Jordanian T.V. series and interviews with native speakers of Jordanian Arabic. The sample of the study consisted of 300 tokens of ʃikil and 200 tokens of omir. The researcher collected the data, then he analysed the functions of these two words. The study found out that ʃikil was used 100 times as a noun meaning 'shape', and 200 times as an evidential particle. Besides, omir was also used as a noun 60 times and 140 times as a negative polarity item. The findings of the study showed that ʃikil has one lexical meaning 'shape', and it evolved by the process of grammaticalization into an evidential particle. ʃikil underwent the process of semantic bleaching, since it lost its content meaning and developed to serve a grammatical function of evidentially. Bedsides, it was decategorized as it lost the grammatical features of nouns, i.e. it cannot be pluralized and cannot accept definite articles. Also ʃikil lost its stress as part of phonetic reduction. Similarly, omir has one lexical meaning 'age' and developed into a negative polarity item. Omir was affected by the process of semantic bleaching and decategorization as it was developed from its original meaning as a noun meaning 'age' into a negative polarity item. Additionally, omir underwent the process of phonetic reduction as it lost stress. The study found out that ʃikil and omir underwent three stages of grammaticalization: semantic bleaching, decategorization, and phonetic reduction.