Thread by @DannyBate4

*udrós 'water' was a PIE adjective

this led to English 'otter', as well as the words for 'otter' in Sanskrit (udrá), Latin (lutra) and Slavic (e.g. Czech vydra)

but, in Greek, it became húdrā 'water snake', origin of the mythological Hydra

yes, 'Hydra' and 'otter' are cognates

"but Danny," asks no one. "Surely Hydra is related to hydro-?"

it is! The hydro- prefix is from Greek húdōr 'water', from the PIE noun *wódr, which shares a root with *udrós

*wódr is also the source of English water, Slavic voda (whence vodka) and Gaelic uisge (whence whisky)

so, otter, hydra, whisky and vodka are in fact related to each other, all deriving from one single PIE root (via *udrós or *wódr)

that single root? PIE *wed- 'water' - a root with so many descendants

(for example, *wed- gives us 'wet'. Surprisingly, it also gives us 'vitriol')

a final cool *wódr fact:

this is Bedřich Hrozný (1879-1952), the Czech philologist instrumental to the decipherment of Hittite and its recognition as Indo-European

it is said that the similarity between German Wasser and Hittite watar (both from *wódr) caused his eureka moment

I did say that that was the last *wódr/*udrós fact...

so here are two Hrozný facts:

1) the Hittite sentence with watar that inspired Hrozný also included the verb stem ezza- 'eat', related to English eat, German essen, Latin edō and Greek esthíō

2) hrozný is Czech for 'awful'