The Spanish word 'muscular' comes from Latin 'muscularis', meaning 'relating to muscles'. This Latin word was formed from 'musculus' (meaning 'muscle') and the suffix '-aris' (meaning 'relating to'). Interestingly, 'musculus' itself literally meant 'little mouse' in Latin, being composed of 'mus' ('mouse') and the diminutive suffix '-culus'. This curious connection between mice and muscles exists because the ancient Romans thought that the movement of some muscles under the skin resembled a mouse running under a blanket!

A simpler and very common related Spanish word is 'músculo' (muscle), which comes directly from the Latin 'musculus'. Understanding this connection makes it easy to remember that 'muscular' simply means 'relating to muscles' - it's just 'músculo' with the relational suffix '-ar' added to it.

English speakers will find it easy to remember this word as it's identical to the English word 'muscular'! Both Spanish and English inherited this word from the same Latin source. Other related English words include 'muscle', 'muscly', and even 'mouse' - remember the ancient Roman observation about muscles looking like little mice moving under the skin!