Homesickness
Etymology
A calque (loan-translation) of German "Heimweh" ("home-woe"), entering English in the 18th century. Its clinical twin "nostalgia" was coined in 1688 by the physician Johannes Hofer from Greek "nostos" (homecoming) and "algos" (pain) to name the same condition in Swiss mercenaries — homesickness was literally a diagnosis.
noun · /HOHM-sik-nuss/
A distressed longing for home and familiar surroundings while away from them.
What it names
A real, sometimes disabling ache — once thought a medical illness — for a place you can actually return to.
Example
The homesickness hit hardest at dinnertime, when the smell of someone else’s cooking reminded her whose it wasn’t.
Related idea
Homesickness longs for a place you can still reach; nostalgia has drifted to mean longing for a past time you cannot, which is why you can feel nostalgic at home.