partial shadow

• penumbraRegion of partial illumination
• eclipseCelestial body blocks another
• dappledMarked with spots
• silhouetteFilled-in outline shape
• twilightLight after sunset

dimness · shade · half-light · gloom · murky · hazy · filtered · canopy · overcast · dusky · faint · mottled · veil · gauze · diffuse · softened · obscured · gradient