Customary, usual, or normal: the train's regular schedule.
Orderly, even, or symmetrical: regular teeth.
In conformity with a fixed procedure, principle, or discipline.
Well-ordered; methodical: regular habits.
Occurring at fixed intervals; periodic: regular payments.
Occurring with normal or healthy frequency.
Having bowel movements or menstrual periods with normal or healthy frequency.
Having equal sides and equal angles. Used of polygons.
Having faces that are congruent regular polygons and congruent polyhedral angles. Used of polyhedrons.
Not varying; constant.
Formally correct; proper.
Having the required qualifications for an occupation: not a regular lawyer.
Informal Complete; thorough: a regular scoundrel.
Informal Good; nice: a regular guy.
Botany Having symmetrically arranged parts of similar size and shape: regular flowers.
Grammar Conforming to the usual pattern of inflection, derivation, or word formation.
Ecclesiastical Belonging to a religious order and bound by its rules: the regular clergy.
Mathematics
Having equal sides and equal angles. Used of polygons.
Having faces that are congruent regular polygons and congruent polyhedral angles. Used of polyhedrons.
Belonging to or constituting the permanent army of a nation.
n.
Ecclesiastical A member of the clergy or of a religious order.
A soldier belonging to a regular army.
A dependable loyal person: one of the party regulars.
A clothing size designed for persons of average height.
A habitual customer.
[Middle English reguler, living under religious rule, from Old French, from Late Latin rēgulāris, according to rule, from Latin rēgula, rod, rule; see reg- in Indo-European roots.] reg'u·lar'i·ty (-lār'ĭ-tē) n., reg'u·lar·ly adv.
[reg-yuh-ler-lee] 
yə