affine vs rare

To refine. 

Of or pertaining to a function expressible as f(⃑x)=A⃑x+⃑b (where A is a linear transformation and ⃑b is a constant), which, regarded as a transformation, maps parallel lines to parallel lines and finite points to finite points. 

Assigning finite values to finite quantities. 

Of two materials, having mutual affinity. 

To rear, bring up, raise. 

To rear, rise up, start backwards. 

Thin; of low density. 

Very uncommon; scarce. 

Particularly of meat, especially beefsteak: cooked very lightly, so the meat is still red. 

Good; enjoyable.