1. (Science: botany) The fruit of the oak, being an oval nut growing in a woody cup or cupule.
2. A cone-shaped piece of wood on the point of the spindle above the vane, on the mast-head.
Origin: as. Aecern, fr. Aecer field, acre; akin to D. Aker acorn, Ger. Ecker, Icel. Akarn, dan. Agern, goth. Akran fruit, akrs field; orig. Fruit of the field.