square – four equal sides, four 90 degree angles; a special type of rectangle
rectangle – two sets of equal sides, four 90 degree angles; a special type of parallelogram
parallelogram – two sets of equal, parallel sides
rhombus – two sets of parallel sides, all four sides equal
equilateral triangle – all three sides equal
right isosceles triangle – two sides equal; one 90 degree angle
scalene triangle – no sides are equal
pentagon – five sides figure
hexagon – six sided figure
octagon – eight sided figure
regular – simply put, it means all sides are equal. A square would be a regular rectangle. An equilateral triangle would be a regular triangle. A regular pentagon would just mean that all five sides of the pentagon are the same length.