The Spanish word 'intercostal' comes from combining Latin elements: the prefix 'inter-' meaning 'between', and 'costalis' meaning 'relating to ribs'. The Latin 'costalis' itself was formed from 'costa' (meaning 'rib' or 'side') and the suffix '-alis' (meaning 'relating to'). So literally, 'intercostal' means 'between the ribs', and it maintains this anatomical meaning in modern Spanish.

A simpler related Spanish word is 'costal', which means 'relating to the ribs' or 'coastal'. This comes directly from the same Latin root 'costa' meaning 'rib' or 'side'. Interestingly, in Spanish, like in English, this word can also refer to the coast or seashore, as the coast was viewed as the 'side' or 'rib' of the land.

English speakers might recognize the relationship to several common English words. 'Coastal' and 'coast' come from the same Latin root 'costa'. While in anatomy we preserved the 'rib' meaning (as in 'intercostal muscles'), the word 'coast' evolved to primarily mean the shoreline or edge of the land. The English word 'intercostal' is also a direct cognate, having exactly the same meaning and etymology as its Spanish counterpart.