Merriam-Webster Collegiate Dictionary - nostalgia

 noun  Etymology: New Latin, from Greek nostos return home + New Latin -algia; akin to Greek neisthai to return, Old English genesan to survive, Sanskrit nasate he approaches  Date: 1756  1. the state of being homesick ; homesickness  2. a wistful or excessively sentimental yearning for return to or of some past period or irrecoverable condition; also something that evokes ~  • nostalgic adjective or noun  • nostalgically adverb  • nostalgist noun