versant

A gadget lover, Alexander is known to roll up his sleeves to become versant with the latest security technologies.

From Reuters ● May 26, 2013

I expected a corresponding formation upon the opposite eastern versant: we found only a huge crest, a spine of black plutonic rock, intensely ugly and repulsive.

From The Land of Midian — Volume 2 by Sir Richard Francis Burton

I have heard from mariners and skilful pilots, much versant in the Indian seas, and have seen in their writings, that these seas contain 12,700 islands, inhabited or desert.

From A General History and Collection of Voyages and Travels — Volume 01 Arranged in Systematic Order: Forming a Complete History of the Origin and Progress of Navigation, Discovery, and Commerce, by Sea and Land, from the Earliest Ages to the Present Time by Robert Kerr

Llan means a level place generally, as most of your readers who are versant in those subjects know.

From Notes and Queries, Vol. IV, Number 110, December 6, 1851 A Medium of Inter-communication for Literary Men, Artists, Antiquaries, Genealogists, etc. by Various

On the western versant of the Andes of Ecuador there are three river systems of considerable size—the Mira, the Esmeraldas and the Guayas.

From Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 10 "Echinoderma" to "Edward" by Various