lonelyI've been lonely since my friends moved away.
lonesomeUSI'm feeling lonesome.
isolatedI wouldn't like living out in the country - I'd feel isolated from the rest of the world.
forlornliteraryThe characters, a flighty heiress and her forlorn suitor, are a delight.
desolateAfter the market crash, desolate financiers left the field.
desolatedWe are desolated, Colonel, that the regiment is to leave.