The Spanish word 'década' (meaning 'decade') comes from Late Latin 'decada', which in turn derives from the Ancient Greek word 'δεκάς' (dekas), meaning 'a group of ten'. The Greek word contains the root 'dek-' meaning 'ten', which has remained remarkably stable in meaning throughout its evolution into modern Spanish.

Several common Spanish words share this same ancient root meaning 'ten', including: 'diez' (ten), 'décimo' (tenth), 'decimal' (decimal), and 'decena' (group of ten). All these words preserve the basic meaning of counting by tens or grouping in tens.

English speakers can easily remember 'década' by connecting it to several similar English words that share the same Greek origin: 'decade' (ten years), 'decimal' (based on ten), and 'decagon' (ten-sided shape). The English word 'decade' is particularly helpful since it's almost identical in both spelling and meaning to the Spanish 'década' - they just differ in the placement of the accent mark!