pro·to·cer·a·tops 
(prō′tō-sĕrə-tŏps′)
(prō′tō-sĕrə-tŏps′)n.
A small herbivorous ceratopsian dinosaur of the genus Protoceratops of the Cretaceous Period, characterized by a bony frill on the back of the skull and a beaked mouth.
[New Latin Prōtocerātōps, genus name : Greek prōto-, proto- + Greek keras, kerāt-, horn; see ker-1 in the Appendix of Indo-European roots + Greek ōps, eye, face; see okw- in the Appendix of Indo-European roots.]
- sodium chloride
- sodium citrate
- sodium cyanide
- sodium cyclamate
- sodium dichromate
- sodium fluoride
- sodium glutamate
- sodium hydrosulfite
- sodium hydroxide
- sodium hypochlorite
- sodium hyposulfite
- sodium lauryl sulfate
- sodium nitrate
- sodium perborate
- sodium peroxide
- sodium phosphate
- sodium-potassium pump
- sodium propionate
- sodium silicate
- sodium sulfate
- sodium sulfide
- sodium sulfite
- sodium thiopental
- sodium thiosulfate
- sodium tripolyphosphate