alliaceous (ăl-ē-Ā-shəs) Definition (Adjective) Of a smell or taste: resembling that of garlic or onions, garlicky; also having such a smell or taste. In Context "In the Middle Ages in southern Europe, food tended to be alliaceous because garlic helped disguise the fact that warm temperatures had turned some of the ingredients bad." Mark Morton, Cupboard Love: A Dictionary of Culinary Curiosities, Second Edition, 2004.