The Spanish word 'copita' comes from combining the Spanish word 'copa' (meaning 'cup') with the diminutive suffix '-ita'. The base word 'copa' itself derives from the Latin word 'cuppa', meaning 'cup'. The diminutive suffix '-ita' makes the word mean 'small cup' or 'little cup'.

This is a classic example of Spanish word formation using diminutive suffixes, which are very common in Spanish to express smallness or endearment.

The most obvious related Spanish word is 'copa', which means 'cup' or 'wine glass'. While 'copa' refers to a regular-sized drinking vessel, 'copita' specifically refers to a smaller version. You might hear 'copa' used in contexts like 'una copa de vino' (a glass of wine), while 'copita' might be used for a small glass or shot glass, as in 'una copita de jerez' (a small glass of sherry).

The English word 'cup' is actually related to 'copita', as both can be traced back to the Latin 'cuppa'. This connection is fairly easy to see and remember since both words refer to drinking vessels and sound somewhat similar. Another related English word is 'cuppa', which is informal British English for a cup of tea, also derived from the same Latin root.