Definition of "spectral"

The day itself was miserably dull; a thick fog shut out the landscape, while a few of the nearer trees alone were visible, spreading out their thin spectral arms on the murky air.

1837, L[etitia] E[lizabeth] L[andon], “The Marriage Morning”, in Ethel Churchill: Or, The Two Brides. […], volume I, London: Henry Colburn, […], page 202

Agitated by a multitude of curious thoughts, I retired to my room, that night, prepared to encounter some new experience of a spectral character.

1859 December 13, Charles Dickens, “The Ghost in Master B’s Room”, in Charles Dickens, editor, The Haunted House. The Extra Christmas Number of All the Year Round […], volume II, London: […] C. Whiting, […], page 27, column 2