A decade is count of 10 consecutive years. For instance when you refer to the period between 2010 to 2019. That is a decade. The word Deca also means 10. You will notice that the word decade starts with the letters d-e-c suggesting a ten of something. In this case ‘deca’ here means “ten of years”.
A hundred years is known as a century. Here ‘cent’ means a hundred hence 100 is century. A thousand years is a millennium. Here mill meaning a thousand.
decathlon – a kind of sport where each participant takes part in 10 track and field events.
decathlete – an athlete who takes part to compete in decathlon.
decametric – unit of measuring in metric system meaning 10 metres.
decahedron – a figure with 10 faces
decaliters – unit of measuring capacity meaning ten of liters.
decalogues – this is the ten commandments given by God in the book of Exodus in the bible.