adj ·4 syllables ·Common ·High school level

Definitions

Adjective

1. 1
   Lacking substance; not real or strong.

   "The bridge was insubstantial and would not safely carry a car."

Adjective

1. 1
   lacking material form or substance; unreal wordnet
2. 2
   lacking solidity or strength wordnet
3. 3
   lacking in nutritive value wordnet

Synonyms

All synonyms

flimsyunsubstantialadulteratedaeriformaeryairy

Antonyms

All antonyms

corporealmassivesubstantial

Example

More examples

"The judge found the evidence of his guilt insubstantial."

Etymology

Probably from Middle French insubstantiel, from Latin insubstantiālis, from in- + substantiālis.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.