| an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle. |
| a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison. |
adventitious ad·ven·ti·tious (ād'věn-tĭsh'əs, -vən-)
adj.
Arising from an external source or occurring in an unusual place or manner; extrinsic.
Occurring accidentally or spontaneously, not caused by heredity.
Adventitial.