half-seen

half-seen (not comparable)

1. Not fully or clearly seen; with the view obscured in some manner.
   • 1886 October – 1887 January, H[enry] Rider Haggard, She: A History of Adventure, London: Longmans, Green, and Co., published 1887, →OCLC:

     Then in a moment they acquired a vacant, terrified stare, as though they were striving to realise some half-seen horror.