The Spanish word 'placita' comes from adding the diminutive suffix '-ita' to the word 'plaza', meaning 'plaza' or 'square'. 'Plaza' itself has an interesting history - it comes from Latin 'platea' meaning 'wide street', which in turn was borrowed from Ancient Greek 'plateia' (πλατεῖα), also meaning 'wide street'. So a 'placita' is literally a 'little plaza' or 'small square'.

The change from 'platea' to 'plaza' shows a common sound change in Spanish where the Latin '-ea' ending often became '-a'. The diminutive '-ita' is one of the most common and productive diminutive suffixes in Spanish, used to indicate something is small or endearing.

The most obvious related Spanish word is 'plaza', which means 'plaza' or 'town square'. While 'plaza' refers to any public square or marketplace, 'placita' specifically refers to a smaller version of this. This relationship is very transparent since 'placita' is simply 'plaza' with the diminutive suffix.

English has borrowed both 'plaza' and 'place' from this same ultimate source. 'Plaza' was borrowed directly from Spanish, while 'place' came through French from the same Latin root 'platea'. The meaning evolved from 'wide street' to a more general sense of 'space' or 'location'. You might also see 'placita' used in English, particularly in the southwestern United States, where it refers to a small plaza or courtyard, maintaining its Spanish meaning.