Saudade

It turns out that there is an equivalent to the Wesh hiraeth in another language; Portuguese's suadade:

The famous saudade of the Portuguese is a vague and constant desire for something that does not and probably cannot exist, for something other than the present, a turning towards the past or towards the future; not an active discontent or poignant sadness but an indolent dreaming wistfulness.

"An indolent dreaming wistfulness". Precisely.