Webster's Revised Unabridged Dictionary · 1913

Fastigiate

Fastigiate , adjective

[Latin fastigium gable end, top, height, summit.]

1.
Narrowing towards the top.
2.
(Botany) Clustered, parallel, and upright, as the branches of the Lombardy poplar; pointed.
3.
(Zoology) United into a conical bundle, or into a bundle with an enlarged head, like a sheaf of wheat.

Also: Fastigiated