The Spanish word 'pastilla' (meaning 'pill' or 'tablet') has an interesting journey from ancient Greek through Latin. It starts with the Greek word 'πάστη' (paste), which meant 'barley porridge'. This word evolved into the Latin 'pasta' meaning 'paste' or 'dough'. When this word entered Spanish as 'pasta', it kept the same meaning of 'paste' or 'dough'. The diminutive suffix '-illa' was then added to 'pasta' to form 'pastilla', literally meaning 'little paste', which came to specifically refer to a small, formed piece of medicine - a pill or tablet.

The most obvious related Spanish word is 'pasta', which means 'paste' or 'dough' and is also commonly used to refer to 'pasta' as in the food. You can think of a 'pastilla' as a small, formed piece of 'pasta' or paste, which makes sense given that pills are small, formed pieces of medicinal paste or powder.

English speakers can relate 'pastilla' to several familiar words that share the same Greek root. The word 'paste' is directly related, coming from the same Greek root 'πάστη'. Similarly, 'pasta' entered English from the same Latin source. The connection makes sense when you think about how paste, pasta, and pills all involve substances that have been mixed or kneaded into a particular form.