[1835–45; py- + -in2]This word is first recorded in the period 1835–45. Other words that entered Englishat around the same time include: catch-up, communism, faceplate, protein, squeegee-in is a noun suffix used in a special manner in chemical and mineralogical nomenclature(glycerin; acetin, etc.). In spelling, usage wavers between -in and -ine. In chemistry a certain distinction of use is attempted, basic substances havingthe termination -ine rather than -in (aconitine; aniline, etc.), and -in being restricted to certain neutral compounds, glycerides, glucosides, and proteids(albumin; palmitin, etc.), but this distinction is not always observed