penumbral.

1. Relating to or lying in partial shadow.

2. Obscure, indeterminate, or lying at an uncertain boundary.

Use it for

Words that belong together

• penumbral light
• penumbral region

On the page

Penumbral light softened the far end of the gallery.

The probe entered a penumbral region before the planet blocked the star entirely.

Usage notes

Primary category: literary. Forms: Comparative more penumbral; superlative most penumbral where gradation is meaningful. Legacy lexical fields mirror sense 1 only. Use numbered sense fields for all meanings.