-da suffix used to derive nouns denoting the result of an action, like yulda "draught, the amount drunk" (the stem YUL is here given the meaning "drink"). (PE17:68) Cf. also carda "deed" (q.v.) vs. the verb car- "do".
Quenya
suhto
draught
-da
draught, the amount drunk
yulda
draught, something drunk, a drink, the amount drunk
yulda noun "draught, something drunk, a drink, the amount drunk", pl. yuldar (Nam, PE17:63, 68, RGEO:66). See -da regarding etymology.
suhto noun "draught" (SUK)