The difference between Completeness and Completion

Completeness as a noun:

the state or condition of being complete

Completeness as a noun (logic):

The property of a logical theory that whenever a wff is valid then it must also be a theorem. Symbolically, letting T represent a theory within logic L, this can be represented as the property that whenever T \vDash \phi is true, then T \vdash \phi must also be true, for any wff φ of logic L.

Completion as a noun:

The act or state of being or making something complete; conclusion, accomplishment.

Completion as a noun (legal):

The conclusion of an act of conveyancing concerning the sale of a property.

Completion as a noun (American football):

A forward pass that is successfully caught by the intended receiver.

Completion as a noun (mathematics):

The act of making a metric space complete by adding points.

Completion as a noun (mathematics):

The space resulting from such an act.