How to understand the etymology from the American Heritage Dictionary?

Question

I look up the word 'frangible'. Its etymology shows

[Middle English, from Old French, from Medieval Latin frangibilis, from Latin frangere, to break; see bhreg- in the Appendix of Indo-European roots.]

Does it mean this is

• a Middle English word
• borrowed from Old French
• borrowed from Medieval Latin 'frangibilis'
• derived from Latin 'frangere'

Answer 1

Yes, mostly. It is first attested in Middle English; it is borrowed from Old French frangible, which is borrowed from Medieval frangibilis (an alternative analysis which they do not adopt is that the Middle English comes from Medieval Latin and not Old French). The step "from frangere" involves a different sense of "from". The chain from frangible to frangibilis is a series of historical "same word, added to a different language". Latin frangibilis isn't "from" frangere in the same way, rather, frangere, frangere, frangō etc all derive synchronically in Latin from the same root, and one of the conventions for identifying roots in Latin is to give the infinitive (or, the 1st singular present).