1. immune to attack; incapable of being tampered with
- an impregnable fortress
2. capable of conceiving
3. incapable of being overcome, challenged or refuted
- an impregnable argument
- impregnable self-confidence
Sentences with impregnable as an adjective:
- Following treatment, twenty percent of previously infertile females were impregnable.Application of the compound rendered the non-porous surface impregnable.