Dictionary.net

• any worm of the Chaetognatha; transparent marine worm with horizontal lateral and caudal fins and a row of movable curved spines at each side of the mouth

2006 - WordNet 3.0
By Princeton University

• any worm of the Chaetognatha; transparent marine worm with horizontal lateral and caudal fins and a row of movable curved spines at each side of the mouth

2011 - English Dictionary Database
By DataStellar Co., Ltd