Nostalgia comes from a Greek word meaning "return home," but its meaning has been extended to indicate a desire to return in thought or in fact to a former time in one's life. Homesickness (home plus sick) is illness, depression, or sadness caused by a longing for home; it is both more specific and more restricted in meaning than nostalgia."Several young soldiers in this company are suffering from homesickness." "Thoughts of his childhood home and happy youth caused a wave of nostalgia to sweep over the weary old man." The adjectives nostalgic and homesick convey the same primary meanings as the nouns from which they are formed: "This young traveler was often homesick and lonely." "That autobiography is a nostalgic account of the author's first thirty years."
Dictionary of problem words and expressions. Harry Shaw. 1975.