Order of brachiopods (Brachiopoda), with rostrate shells, a functional pedicle, and a delthyrium partly restricted by a pair of deltidial plates. The shell is usually impunctate. They appeared first in the Middle Ordovician. The order contains about 250 genera, most of which are extinct.
Rhynchonellida
- unknot
- unknown
- unknown host
- unlimited liability
- Unlisted Securities Market
- unloading
- unloading joint
- unlock
- unmarshalling
- unmoderated newsgroup
- unmoved mover
- unnil-
- unofficial economy
- unordered tree
- UNOX process
- unpack
- unpaid labour
- Unrepresented Nations’ and Peoples’ Organization
- Unruh effect
- unsaturated
- unsaturated model
- unsaturated zone
- unsaturation index
- unscheduled maintenance
- unsecured loan