Dirt Surfaces:
Fast - Dry, even and resilient. Dry to the point of needing to be watered down by the maintenance department.
Wet Fast - A brief burst of rain over a fast track can sometimes leave a thin layer of water over the formerly dry surface that produces times as fast, or faster than, a dry track.
Sloppy - A wet track with visible, standing water on the surface, but that is still firm beneath and may still produce good times.
Sealed - A dirt track may be packed down (and not harrowed) in anticipation of heavy rains so that water will run off the surface rather than being absorbed into the track. Sloppy tracks can also be sealed to even the racing surface (for safety) and help float some of the water out of the track so it will run off the surface.
Muddy - A wet track where the moisture has settled deeper into the track and which produces much slower race times.
Good - Generally a drying track that still has too much moisture in it to be considered fast. A track can also be listed as good on the way from fast to sloppy.
Turf (Grass) Surfaces:
Firm - Firm, dry, resilient grass surface. Corresponds to fast on a dirt surface.
Good - Contains more moisture than a firm course and offers slightly more give.
Soft - Course contains a significant amount of moisture and horses cut deep hoof marks into the surface when racing.
Yielding - Very wet grass course into which horses sink very deeply when running.
Heavy - A deep, often waterlogged, course that is very tiring to run on and produces very slow times.
Hard - A turf course that has not seen rain for an extended period and is so dry the grass is dying and horses kick up a cloud of dust as they run over it.