Matching Pairs Deci-/Deca-Online version Greek Prefix by Nohelani Day 1 decibel 2 decathlon 3 decimeter 4 decapod 5 decade 6 decimate 7 decimal 8 decagon a period of ten years to destroy or reduce a population (of something) by one tenth a unit of measure for sound meaning "one tenth of a bel" a number system based on the number 10 with tenth parts and powers of 10 a polygon with ten straight sides and angles a metric unit of length, equal to one tenth of a meter a crustacean with 10 legs, such as shrimp, crab, or lobster an athletic event in which each competitor takes part in ten events