of or relating to a decimal system / (mathematics, of a logarithm) to the base ten

A period of ten years , particularly such a period beginning with a year ending in 0 and ending with a year ending in 9.

decadence.

Of or related to the number ten. / Of or related to a decade, in its various senses.

In a decadent manner.

Characterized by moral or cultural decline. / Luxuriously self-indulgent.

A person affected by moral decay.

A state of moral or artistic decline or deterioration; decay / The quality of being luxuriously self-indulgent.

plural of decade.

In a decadal manner / With respect to decades