adjective

occurring, found, or done often; prevalent.

salt and pepper are the two most common seasonings

usual,ordinary,customary,habitual,familiar,regular,frequent,repeated,recurrent,routine,everyday,daily,day-to-day,quotidian,standard,typical,conventional,stock,stereotyped,predictable,commonplace,mundane,run-of-the-mill,wonted,widespread,general,universal,popular,mainstream,prevalent,prevailing,rife,established,well established,traditional,traditionalist,orthodox,accepted,in circulation,in force,in vogue

noun

a piece of open land for public use.

we spent the morning tramping over the common looking for flowers