Sipunculus is a genus of worms belonging to the family Sipunculidae.

[1] Sipunculus is a variant spelling of the Latin siphunculus ("little tube"),[2] a diminutive of sipho from Greek σίφων (síphōn, "tube, pipe").

Siphunculus was used for fossilized worm-shaped organisms like Siphunculus scaber by the Welsh naturalist Edward Lhuyd in 1699.

[3] In the next century, the Swedish naturalist Carl Linnaeus used the scientific name Sipunculus nudus for a species of worms in his 1766 Systema Naturae.

[4] In 1814, the French zoologist Constantine Samuel Rafinesque used the feminine form Sipuncula to distinguish the family including S. nudus;[5] this was later elevated to the Sipuncula class, the family being renamed Sipunculidae and the species reorganized into different genera.