Cardinality, Selectivity, Projection and Selection - definitions

From Oracle documentation:

Cardinality

The ratio of distinct values to the number of table rows. A column with only two distinct values in a million-row table would have low cardinality

Selectivity

In a query, the measure of how many rows from a row set pass a predicate test, for example, WHERE last_name = 'Smith'. A selectivity of 0.0 means no rows, whereas a value of 1.0 means all rows. A predicate becomes more selective as the value approaches 0.0 and less selective (or more unselective) as the value approaches 1.0.

Projection

The ability of a SELECT statement to choose a *subset* of the columns in a given table.
In other words, this corresponds to the column listing in the SELECT statement.

Selection

The ability of a SELECT statement to choose a subset of rows in a given table.
In other words, selection corresponds to the WHERE clause of the statement.