1- in your sentence "He's immersed in his work" the word immerse ( here ) means = to completely involve in work Other Examples : She immersed herself in her work. Clare and Phil were immersed in conversation in the corner. .................... 2- immerse has another meaning which is :To cover completely in a liquid; submerge. and immerge : To submerge or disappear in or as if in a liquid * * you asked if the people use "IMMERGE" to express the meaning of the word " IMMERSE " in the second meaning ( not in your sentence ) will immerge and immerse are Synonyms and immege and immerse express the meaning of submerge ( cover in water ( liquid ))