1) allowing air to flow over or around easily (aerodynamic)

2) a short-eared animal like a big rat, often used in experiments; a person allowing herself or himself to be used in medical or other experiments (guinea-pig)

3) (of materials) not allowing water etc to pass through; (of a person) not moved or influenced (by something) (impervious)

4) (in tennis, squash etc) a small error allowing a point to be played again; to allow (a person, thing) (to do something or to happen) (let)

5) not allowing light to pass through; that cannot be seen through (opaque)

6) not closed; allowing (things, people) to go in, out, through; not enclosed, fenced in, barred or blocked (open)

7) the act of allowing something (permission)

8) allowing (too) much personal freedom (permissive)

9) allowing liquid to pass through (porous)

10) allowing light to pass through but not transparent (translucent)