Does this have both meanings of English "weigh", i.e. both "determine the weight of" (the nurse weighed the baby) and "have a certain weight" (the baby weighed ten pounds) ?
Yes, it can mean either: Pwysodd y nyrs y babi or Roedd y babi'n pwyso deg pwys. Note you need the imperfect and not the simple past for the second sentence.
Sorry to comment on a year-old thread, but could you comment on why one sentence needs a simple past and the other doesn't? Does it relate somehow to transitivity? Diolch o flaen llaw!
I wonder whether it's related to the fact that the nurse weighing the baby is a one-time action (the weighing takes maybe a minute) while the baby having a weight of ten pounds is a continuing state (the baby weighed ten pounds all day long, not just while it was lying on the scales).
Ooo nice catch! That seems more likely to be the reason than what I thought.
It can be used for that, but gwasgu would be more common. We generally give only the more usual translations in Duolingo - it isn't a thesaurus!
Pwyso is especially common for "press" with the word botwm: Pwyswch y botwm "Press the button". (You're "supposed" to say Gwasgwch y botwm, according to some, but common usage disagrees.) Geiriadur Bangor lists gwasgu as either "weigh (in)" or "press" and that's it. I don't think he's asking for thesaurus entries ;)
Well, as long as nobody asks for the full set of meanings for it given in the GPC...!