Meanings
- not comparablePertaining to the class Synapsida of animals which have an opening low in the skull roof behind each eye, leaving a bony arch beneath each.
We are synapsid tetrapods, a group of reptiles that almost went extinct 200 million years ago in competition with the better-designed dinosaurs.
1999, Matt Ridley, Genome, Harper Perennial, published 2000, page 26
plural synapsids
- Any animal (all mammals) of the class Synapsida.
Synonyms: mammal-like reptile, stem mammal
Synonyms & antonyms
nounAny animal (all mammals) of the class Synapsida.
More synonyms by meaning
nounextinct reptile having a single pair of lateral temporal openings in the skull
Synonym sets from Open English WordNet, CC BY 4.0.
Origin
- Ancient Greekἁψίς“arch”
- translingualSynapsida
- Englishsynapsid
From translingual Synapsida, from syn- + Ancient Greek ἁψίς (hapsís, “arch”).
More words from translingual, Ancient Greek
Full word history & related roots →Translations
French synapside
- synapsidemember of the Synapsida
Polish synapsyd
- synapsydmember of the Synapsida
Cite this entry
synapsid. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/synapsid
“synapsid.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/synapsid. Accessed November 2, 2026.
WatkinsX Dictionary, s.v. “synapsid,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/synapsid.
Source: synapsid on Wiktionary, CC BY-SA 4.0.