[1640–50; ‹ L tenebr(ae) darkness + -i- + -fic]This word is first recorded in the period 1640–50. Other words that entered Englishat around the same time include: generator, impulse, liaison, sludge, tonic-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