Answer:
Alopecia is the technical term for hair loss and baldness.
It's perhaps most often used to refer to patchy hair loss (alopecia areata) or complete hair loss (Gail Porter, for example) which is either alopecia totalis (bald scalp) or alopecia universalis (entirely bald from top to toe). These are thought to be auto-immune problems.
Androgenic alopecia is 'normal' baldness, male pattern or female pattern which result from an inherited sensitivity to a derivative of testosterone.
There's also traction alopecia which results from hairstyles that cause the hair to be pulled too hard for long periods .. too tight a ponytail or braids.