Corrugated: The ridged lines that run down a downspout
Downspout: A pipe made to carry the rainwater from a gutter system away from the house and toward the ground
Drainage: A system of gutters and downspouts designed to carry water away from the house
Drop outlet: The drop in to attach the downspout to the gutter
Downspout Strap: A strip of material used to attach the downspout to the wall
End cap: A piece of formed aluminum that is crimped over the end of a run of gutter
B-Elbow: Part of the downspout that turns the other direction
A-Elbow: Part of a Downspout that makes the turns
Fall: The slope of a stretch of gutter measured by the vertical rise to the horizontal distance
Fascia Gutter: A gutter style that has a big enough back and is large enough to cover rafter tails to act as a fascia board
Flashing: A 2 x 2 peice of metal that runs under the roofing and into the gutter to protect eve of the roof.
Gauge: The thickness of the gutter material for steel like 26-gauge and 24-gauge, for aluminum the sizes are .027 and .032 of an inch
Gutter: The device that catches water coming off the roof.
Gutter Guards: Also called Gutter Screens- it's a cover installed on top of the gutter to keep out leaves
Hanger: The bracket which is used to hold the face of the gutter in place
Half Round: Type of rain gutter style... used mostly for copper
Leader: Any pipe that carries the water from the gutter to the wall, part of the downspout
Leaderhead: Usually out of copper is a decorative box for the downspouts
Linear Feet: The measurement for a section of gutters per linear foot.
Mitre: Two ends of gutter cut and formed to make a corner
Offset: Parts of a downspout used to go around brick or belly bans
Ogee: A type of rain gutter style like roman ogee
Rain Chain: A  decorative chain used in place of a downspout for visual appeal
Rain Barrel: A  water storage unit installed at the end of a downspout to collect water from the gutters
Run: Any horizontal length of roof or gutter
Splash Block: A plastic, metal, or concrete pad used at the end of the downspouts to further direct water away from the house
Scupper: A square metal box to catch water from a flat roof
Seamless: Rain Gutters that are cut to exact length all in one piece
Slope: Angling of the rain gutter ogee style to help with drainage. Can only be done with gutter that has no wing.
Wedges: Support used to keep gutter level on inverted fascia boards
Wingless: When the gutter is installed without the wing that sits up on top of the roof. (this gutter must be flashed)
With Wing: When the gutter is installed with the wing that sits up on top of the roof. (this gutter doesnt need to be flashed)