- A hagfish; an eel-like marine marsipobranch, Myxine glutinosa, allied to the lamprey, with a suctorial mouth, labial appendages, and a single pair of gill openings.
- The fruit of the hagberry, Prunus padus.
- A fury; a she-monster.
- An appearance of light and fire on a horse's mane or a man's hair.
- A quagmire; mossy ground where peat or turf has been cut.
- (pejorative) An ugly old woman.
- A hagdon or shearwater.
- A small wood, or part of a wood or copse, which is marked off or enclosed for felling, or which has been felled.
- A witch, sorceress, or enchantress; a wizard.
- (transitive) To harass; to weary with vexation.