Fascia is a term which generally describes any vertical surface which spans across the top of columns or across the top of a wall. From the Latin word, meaning "band" or "doorframe"; in architecture. The word is pronounced with the "long-a" sound, rhyming with the Japanese word geisha.
Specifically, used to describe the vertical "fascia board" which caps the end of rafters outside a building, which can be used to hold the rain gutter. The finished surface below the fascia and rafters is called the soffit. A fascia is often installed between the ceiling and the top of wall cabinets in a kitchen, set at a 90 degree angle to the horizontal soffit which projects out from the wall.
In classical architecture, the fascia is the plain, wide band across the bottom of the entablature, directly above the columns. The "guttae" or drip edge was mounted on the fascia in the Doric order, below the triglyph.