palaceous

Borrowed from New Latin palaceus (“spade-like”), from pāla (“spear”) +‎ -āceus.^[1]

palaceous (not comparable)

1. (botany, dated) Of a leaf: having a spade-like shape.
   • 1901, Willard Nelson Clute, Our Ferns in Their Haunts: A Guide to All the Native Species, New York, N.Y.: Frederick A. Stokes Company, page 99:

     Alpina, however, has a black or brownish rachis with scattered palaceous hairs, while that of glabella is entirely smooth and green.

From palace +‎ -ous.

palaceous (comparative more palaceous, superlative most palaceous)

1. (rare, dated) Resembling a palace.
   • 1793, William Andrews, The First Volume of the Poetical Works of William Andrews, Southampton, Hampshire: A. Cunningham, page 12:

     What Domes palaceous! What Cathedrals grand!

   • 1832, Charles Joseph Latrobe, The Pedestrian: A Summer's Ramble in the Tyrol, and Some of the Adjacent Provinces, London: R. B. Seeley & W. Burnside, page 168:

     I had seen many country seats upon the road, the greater part very indifferently posted, and in great want of repair, and I think the very first that had any thing really palaceous about it was at this point, a little before the entrance to Battaglia.

   • 1848, , The Uses and Abuses of Air: Showing Its Influence in Sustaining Life, and Producing Disease: With Remarks on the Ventilation of Houses, New York, N.Y.: J. S. Redfield, page 56:

     So universal is inattention to supplies of fresh air in private dwellings, even the most palaceous, it were almost a work of supererogation to quote an instance of the effects of the impure air upon their inmates, but one case which came to the writer's personal notice, was so striking, as to be deemed worthy of record.