Fastigiate v.

[f. as prec. + -ATE³.] trans. To make pointed at the top like a gable. b. intr. To taper to a point.

1656.  Blount, Glossogr., Fastigiate, to raise up, or grow up to a sharp top.

1733.  in Coles.

  Hence Fastigiated ppl. a., formed like a cone or ridge; ‘roofed, narrowed up to the top’ (Johnson, 1773). † Fastigiation, ‘a making or growing sharp at the top like a pyramid’ (Phillips, 1662).

1647.  H. More, Song of Soul, Notes, 381. Day will hang in the sky many thousand miles off from us, fastigiated into one conicall point.

1668.  Wilkins, Real Char., II. v. § 4. 146. Hawks … noted for … having a fastigiated or rising head, being of an ash colour. called Mountain Falcon.

1730–6.  in Bailey (folio).

1840.  in Humble, Dict. Geol. & Min.