The theory goes like that English ‘daughter’, German ‘Tochter’, Greek ‘thygater’, Irish ‘dear’, Lithuanian ‘dukte’, Russian ‘doch’, are common derivation with the Sankrit root ‘duh’ (to milk), so the word was, according to this theory, originally ‘dogdhri’ = she who milks, to indicate that it was the daughter of a primitive aryan family who did the milking. This charming picture was first drawn by Lassen, quoted with approval by Max Muller, plagiarised by various Indian authors in deservedly obscure writings, re-adopted from Marathi and have now gain an unforseen sanctity by the virtue omission and commission during translation. [ref : Max Muller, Chips from a german workshop (2 vol, London 1868, vol II, pp 22-26)
Unfortunately, it still fail to explain why Aryan languages preserved a common word for ‘she who milks’ without preserving a common word for ‘milk’. It is worthy to note in passing that pastoral life was admitted to be patriarchal and milking the cow comes at a very late stage. So it would not be primitive Aryan, let alone being a woman who milked the cow. It has also been remarked by derisive philologists that there exists a common root-derivation for ‘foot’ but none for ‘hand’ in India-Iranian languages, whence same theory is consistently applied would demand that unseparated Aryan possessed feet, but not hands, which must have sprouted after they are separated. 
Devata and God
In , nowhere author mention a distinction between God and devata. Also, as far as I understand, God is usually taken a singular while devata are always plural. The other word ‘Bhagwan’ which Wiki says means “possessing fortune, blessed, prosperous” also does not fit the definition of ‘God’ as we like to see it these days.
According to this book, devata is connected with light, intelligence ( does not cite any source); and later etymologists have connected it with the root ‘to give’ which makes sense when one consider a Hindi saying ‘Devi to deti hi hai.” but it also does not fit the the idea of God. So is old ‘devata’ were those who gave some materials?
Such an materialistic interpretation from an early civilisation make sense. These days ‘Gods’ or ‘devata’ is connected with spiritual sense. However, one wonders why Indian still offer money to god! Isn’t it hight of materialism in the idea of God? It would be interesting to know when such spiritual conception of God came into being in our civilisation (in any civilisation)? Reading D.D. Koshambi gives an impression that RgVeda mainly (only?) have materialistic interpretation (, chap 4, pp80). So how come people start taking of soul. Unless a civilization produces a surplus which some of its member can appropriate by some cult or custom, thus having a lot of free time to think over, I don’t think one could afford to think about soul (let alone having one)!
Idea of Devata
‘Deva’ seem to have been derived from ‘divyanti’ (devam dhyuti krida va tavanti tevtah). Also in AmarSimha, synonym of Deva have been cited such as amar, nijjar (never ageing), tridhasa (growth, maturity and waste does not affect them), vivudha (always awake), suparvan (with nice tapering fingers), sumans (because they accomplish what they desire), lekha (because their palms and neck are nicely marked by lines, not corny by manual work).
The root ‘de’ is not very far from the explanation of the commentator who says ‘dataro abhimtana bhaktebhya :’ . Another derivation which follows this ‘tejaswat diptya va’ and he adds ‘artha: saman: | div sambanidhno va deva”. Further the entry says ‘dhytthana ityartha: deva rashmaya uchyate ||”
See this discussion for some more inputs.
(This is for those who does not like the idea of Westerner studying Indian sacred text because the meaning is often lost in Sanskrit translation).
One of the most wonderful property of Sankrit has been its formal grammar which is contained in two books : rules of grammar in ‘ashtadhyayi’ and root words in ‘amarkosha’. It is the first known work of ‘context free grammar’ or Noam Chomsky forms. When one takes the root words and apply a rule to forms new words. If you wonder how one can construct 330 million gods and give them distinct names, it is your clue! On these lines, it is very hard to agree that translation of Sankrit can be very ambiguous (if done properly), whether done by a Indian or a non-Indian. If I take the liberty to exaggerate, It’d be like saying that a C-program will behave differently if compiled by an Indian or American. However, there is no denial that root words do often change their meanings over time.
 ‘An Introduction to the Study of Indian History’, D. D. Kosambi
 Devata ‘Gods and Goddesses of Hindus’, K. D. Basu