Clocks and Periods

Clocks noun - European weed naturalized in southwestern United States and Mexico having reddish decumbent stems with small fernlike leaves and small deep reddish-lavender flowers followed by slender fruits that stick straight up; often grown for forage.

Periods and clocks are semantically related. In some cases you can use "Periods" instead a noun "Clocks".

Clocks and periods are semantically related. Sometimes you can use "Clocks" instead a noun "Periods".