Where does “unnavigatable” come from?

unnavigatable (English) comes from English navigatable, from English navigate, from Latin nāvigātus, from Latin nāvigō, from Latin nāvis, from Proto-Italic naus, from German hinaus, from German aus — out, outward.

Ancestry of “unnavigatable”, step by step

StepLanguageWordMeaning
1EnglishnavigatableNavigable
2EnglishnavigateTo plan, control and record the position and...
3Latinnāvigātussailed, having been sailed, navigated, having been navigated, travelled, having been travelled
4Latinnāvigōto sail, navigate, seafare, embark
5Latinnāvisship, boat, vessel; a fleet in the plural
6Proto-Italicnaus
7Germanhinausout
8Germanausout; over; finished; done; up; off
9Old High Germanūzout
10Proto-West Germanic*ūtout, outward
11Proto-Germanicūtout, outward
12Proto-Indo-Europeanúdout, outward
Every word from Proto-Indo-European údEvery word from Proto-Germanic ūtEvery word from Proto-West Germanic *ūt