Here I am again with a speculation. This time, it is about the etymology of the word bdud rtsi (amṛta). I am not aware of speculations by anyone else. When we think of the words bdud (māra/mṛtyu) and bdud rtsi (amṛta), we notice that former is something bad and the latter something good, although the only difference between the two words is rtsi. So what do bdud and rtsi mean? I do not know any other word that contains the syllable bdud. I also do not know if there are other words that are cognate with the word bdud. Of course, we know words such as dud (in dud ’gro “animal”) and ’dud pa (“to bow down” or “to respect”) which seem to be certainly linked with each other, and also words such as mdud pa (“knot”), sdud pa “to gather,” “to abbreviate,” but how is bdud, if at all, is related with these words? By the way, I looked up OTDO and some meanings of bdud are not clear to me. I do not know any instance where bdud is used as a verb. But I wonder if bdud once had the verbal meaning of “to succumb” (i.e. both in the sense of (a) “yield, give in, give way, submit, surrender, capitulate, cave in; be overcome by, be overwhelmed by, be conquered by, be beaten by” and (b) “die from, die of, pass away as a result of, be a fatality of”). If we can consider this a possibility, then we could also consider that dud, ’dud (cf. gdud), sdud, mdud (cf. mthud and ’thud) and bdud to be all cognates with each other and as having the basic and shared meaning of “to bend” or “to bow.” In the case of dud or ’dud, the meaning “to bend” or “to bow” seems self-evident. What about sdud? Even here, the act of “gathering” or “abbreviating” seems to suggest the semantic nuance of “bending or forcing or bringing certain things to come together.” What about mdud (as in mdud pa mdud “to tie a knot” or “to form a knot”)? It is clear that forming a knot with a rope necessarily implies “bending the rope” so as to form a certain loop and shape. And finally bdud should then mean to “bow down” (i.e. capitulate to) factors, events, or processes over which one has no autonomy. Consider the idea of the four kinds of bdud (māra) found in Buddhism. In short, bdud (as a noun) should thus mean all those forces or factors to which one inevitably and invariably bdud (“succumbs”).
Now what about rtsi? The meaning of rtsi seems relatively clear. Consider other Tibetan words such as sbrang rtsi (“nectar” or “honey”), tshon rtsi (“color pigment”), dkar rtsi (“white paint/glue”), rdo rtsi (“glaze for porcelain”), bkrag rtsi (“glaze”), snum rtsi (“oily substance”), and so on. So it seems that rtsi is to be understood in the sense of some kind of “sticky substance” and each kind may have its own specific function. The phrase rtsis zin pa (“to be suffused by”) should be understood in the same context. But more specifically bTsan-lha’s brDa dkrol gser gyi me long (s.v. rtsi) gives two meanings of the word, namely, (a) “to be beneficial” (phan pa [= sman pa]) and (b) “wind” (rlung). Perhaps the latter meaning presupposes the former. That is, for example, “oxygen” (as a kind of rlung) is of course “beneficial” for sustaining life. The words phan pa and sman pa (as verbs) seem to be synonymous. That which is “beneficial” is also “medicinal.”
In sum, etymologically bdud rtsi seems to mean “a kind of sticky substance (rtsi) or a medicinal substance (rtsi) which serves as a kind of remedy, panacea or elixir against forces or factors to which one inevitably and invariably succumbs (bdud).”