Standard Lemma guide

synapsid

adj · noun · 3 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

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  • UK: /sɪˈnapsɪd/

1

adj

Meaning 1

Pertaining to the class Synapsida of animals which have an opening low in the skull roof behind each eye, leaving a bony arch beneath each.

Definition source: English Wiktionary via Wiktextract

Usage: not-comparable

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

noun

Meaning 2

Any animal (all mammals) of the class Synapsida.

Definition source: English Wiktionary via Wiktextract

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

3

noun

Meaning 3

extinct reptile having a single pair of lateral temporal openings in the skull

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: synapsid reptile

Antonyms: none provided

Broader terms: reptile, reptilian

Narrower terms: therapsid, protomammal, ictodosaur, pelycosaur, edaphosaurus, dimetrodon

History

Etymology

From translingual Synapsida, from syn- + Ancient Greek ἁψίς (hapsís, “arch”).

Across languages

Translations

2 source translations are retained for this English entry.

  • French: synapside — member of the Synapsida
  • Polish: synapsyd — member of the Synapsida