I discovered today that there is a connection between the Gaelic word for knowledge, information, news – fios in Irish and Scottish Gaelic, fys in Manx – and the English words video and wit.
Their roots can all be traced back to the Proto-Indo-European root woid-/wid- (to see/to know), which, according to the OED, is also the root of words such as the Sanskrit वेदा (veda – knowledge); the Latin vidēre to see); the Welsh gwybod (to know); the Lithuanian véidas (face); and the Greek ἰνδάλλεσθαι (to appear).
The Irish and Scottish Gaelic word fios is also related to the word fionn (white, fair, pale; sincere, true, certain; small; fine, pleasant), which is how I discovered this while putting together a new page of Scottish Gaelic colours – you can see how easily I get distracted. This doesn’t worry me as it’s all very interesting.
Also connected is ‘guide’, through French, from Frankish ‘witan’ http://www.etymonline.com/index.php?term=guide , cognate with German ‘wissen’
Could there also be a connection with ‘guise’ and the suffix ‘-wise’ (as in ‘clockwise’, ‘otherwise’ etc.)?
Wiktionary indicates that ‘-wise’ is derived from ‘wise’ meaning ‘way, manner’, which in turn derives from the same Proto-Germanic root that was borrowed into Old French as ‘guise’ and ultimately comes from the same PIE root as the rest of the words in this article, so yes.
There is also the old Russian word for “to know”, “vedat'”. (Russian and Sanskrit have some surprisingly similar words.)
I can see the relation to German “wissen” and Swedish “veta”, both “to know”.
‘Idol’ from Greek εἴδωλον (originally “appearance”) also comes from the *weid root.
I learned a few years ago that the surname Mackinnon is originally Gaelic mac Fhinghuin ‘son of the fair one’. And for other names, there is the Welsh Gwyn and Gwen, and the Breton surname Gwin spelled Gouin in French. (One Lomer Gouin was a premier of Quebec a century or so ago.)
And then there is the old Roman-era city of Vindobona (white base) now known as Wien, Vienna and so on.
The Slavic (here as Late Common Slavic but virtually unchanged in OCS) *věděti “to know (be aware of)” is one of the few preserved athematic verbs and exceptional within the system because it retained a 1sg form *vědě (besides the more regular variant *věmь < woid-mi) which uniquely continues a PIE perfect middle form. So it probably exemplifies the semantic development: I have seen → I know.
I have to add that the zero-grade forms (that is, non-perfect forms) are continued by *viděti “to see” which conjugates ‘thematically’ like almost all Slavic verbs.