Modern Islamic Boarding School of Gontor, commonlycalled Pondok Gontor, is the pioneer of language teachingamong pondok pesantrens– islamic boarding schools- inIndonesia. Its reputation is well known nationally andinternationally. There have been many researches on itseducation systems, yet no particular concerns have beengiven to the study of language used among santris(students of pesantren). For this concern, this paper aims tostudy the internal condition of language used daily bysantris in their daily life. This paper focuses on semanticchanges, which occur in santri’s daily language. Due to theusage of Arabic—the language that is the most commonlyused by santris— the main focus of this paper is lexicalsemantic changes in Arabic language. In additions, thispaper analyzes the problems in using words. This paperfinds that semantically some words are used incorrectly.For example, some nouns are used as verbs, and some otheras adjectives. The semantic changes occur amongst santrisseem to be influenced by their first language or their mothertongue. Deeper study needs to be conducted in order to geta whole description of the usage of language by the santris.