The Spanish verb 'festejar' (to celebrate) traces its origins to the Latin word 'festus' meaning 'festive'. This Latin word gave rise to 'festa' meaning 'feast' or 'festival'. The word then evolved into the Italian 'festeggiare' meaning 'to celebrate', which was ultimately borrowed into Spanish as 'festejar' with the addition of the common Spanish verb suffix '-ar'.

This etymology shows how the concept of festivity and celebration has remained remarkably consistent from Latin through Italian to modern Spanish.

Several common Spanish words share this festive etymology, including 'fiesta' (party, celebration), which is a more commonly encountered word for Spanish learners. The noun 'festival' is also related, as well as 'festivo' (festive, holiday). All these words carry the core meaning of celebration and festivity from their Latin root.

English speakers can easily connect 'festejar' to several familiar English words that share the same Latin origin, such as 'feast', 'festival', 'festive', and 'festivity'. All these words maintain the connection to celebration and joyous occasions, making it easier to remember the meaning of 'festejar'. The English word 'fête' (a festival or celebration), borrowed from French, is also a cousin of 'festejar'.