[1790–1800; gas + -i- + -form]This word is first recorded in the period 1790–1800. Other words that entered Englishat around the same time include: backhanded, cutout, idealism, ideology, rationalism-i- is the typical ending of the first element of compounds of Latin words, as -o- is of Greek words, but often used in English with a first element of any origin,if the second element is of Latin origin. Other words that use the affix -i- include: Frenchify, cuneiform; -form is a combining form meaning “having the form of”. Other words that use the affix-form include: arcform, iodoform, stratiform, tectiform, terraform