This research paper tackles the loanwords used as jargons within the field of car mechanics. In this field, many loanwords are noticed to be used and they become part of car mechanics everyday language within their career context of situation. But these words are modified in one way or another to be more approximate to Mosuli Arabic words. Actually these loanwords are adapted to Mosuli Arabic linguistic systems. This paper aims at investigating loanwords adaptation processes. The analysis of the data reveals that loanwords are phonologically and morphologically adapted to Mosuli Arabic. The data are collected from the field by the researcher adopting two ethnographic method: observation and interview. Then a list is made that contains the loanwords used as car mechanics jargons, their transcribed form, their meaning in English and their source language. The data were analysed adopting a modified linguistic model depending on more than one study. The study has found the loanwords are adapted to Mosuli Arabic phonologically through lighting/Tarqeeq (vs. Darkening/Tafkhim), substitution, assimilation, metathesis, elision, addition and doubling(gemination), and morphologically, by adaptation to number, gender, possession, the definite article, negation and word formation (affixation, clipping, acronym, and loan blend). This study paves the way for other researches that may deal with loanwords used in other fields/careers, or to examine loanwords adaptation on the level of semantics.