Sperm motility describes the ability of sperm to move properly through the female reproductive tract (internal fertilization) or through water (external fertilization) to reach the egg. Sperm motility can also be thought of as the quality, which is a factor in successful conception; sperm that do not `swim` properly will not reach the egg in ord.....
Ability of the spermatozoon to move by flagellate swimming. ... (12 Dec 1998) ... 
The ability of sperm to swim. Poor motility means the sperm have a difficult time reaching the egg.
The ability of sperm
Sperm motility: The percentage of all moving sperm in a semen sample. In a semen sample, 50% or more of the sperm should normally be moving rapidly.
The ability of sperm to move and swim quickly.