Welsh has a word - hiraeth - which is a combination of homesickness and nostalgia but is more than either. This is a very interesting site about the Welsh language.
I've also discovered that Portuguese has a word - saudade - which means the same thing.
According to the Y Geiriadur Mawr Welsh hiraeth means 'longing, nostalgia; grief'. It is related to the word hir 'long' and hiraethu 'to yearn; to sorrow'. I wonder if it is a loan-translation of English 'to long'? Portuguese saudade is from Latin solitas and is related to Spanish soledad. (Too bad we don;t have a word solity.) Nostalgia is from the Greek nostos 'return home' and algos 'pain'.
—Ceci n'est pas un seing.