1. any slow moving creature.
2. also called bear animalcule, water bear: any microscopic, chiefly herbivorous invertebrate of the phylum Tardigrada, living in water, on mosses, lichens, etc.
3. slow in pace or movement.
4. belonging or pertaining to the phylum Tardigrada.
Etymology: via Latin tardigradus, from tardus (sluggish) + gradī (to walk).