The Spanish word 'mamacita' comes from combining the word 'mamá' (mother) with the diminutive suffix '-cita'. The base word 'mamá' traces back to the Latin word 'mamma', which meant both 'mother' and 'breast'. This Latin word evolved into Spanish 'mama/mamá', keeping its meaning of 'mother'. When combined with the affectionate diminutive suffix '-cita', it literally means 'little mother', but is used as a term of endearment.

The most obvious related Spanish word is 'mamá', which is the common word for 'mother' in Spanish. This is a simpler and more formal word than 'mamacita'. Another related form is 'mama', which is a more informal or childish way to say 'mother'. The suffix '-cita' is very common in Spanish and is used to form diminutives or express affection, as in words like 'casita' (little house) or 'abuelita' (dear grandmother).

The English word 'mama' or 'momma' is related to Spanish 'mamá' and 'mamacita', as they all ultimately come from the Latin 'mamma'. This is one of those words that appears very similar across many languages because it comes from one of the first sounds babies typically make ('ma-ma'). The English 'mammary' is also related, coming from the 'breast' meaning of Latin 'mamma'.