Motility is a biological term: the ability of an organism or cell to move itself, using its own energy — sperm motility, bacterial motility, gut motility. Mobility is the general word for the ability to move or be moved, and applies to people, vehicles, capital and furniture. Motility is always self-powered; mobility need not be.
The core difference
Both concern movement, but motility is narrow and technical.
- motility — self-generated movement, chiefly biological: sperm motility, intestinal motility.
- mobility — the general ability to move or be moved: reduced mobility, social mobility.
Where each appears
Motility belongs to biology and medicine almost exclusively — you will meet it in fertility testing, microbiology and gastroenterology. Mobility ranges far wider, including figurative uses like social mobility, which describes movement between economic positions rather than physical movement at all.
The roots
Both come from Latin movere, to move. Motility was coined much later and deliberately narrowed to self-propulsion, which is why it kept a precision mobility never had.
Frequently asked questions
What is the difference between motility and mobility?
Motility is the ability to move under one's own power, used in biology. Mobility is the general ability to move or be moved, including being moved by something else.
Where is motility used?
Almost entirely in biology and medicine — sperm motility, bacterial motility, gut motility.
What is social mobility?
Movement between social or economic positions, a figurative use of mobility with no physical movement involved.