The Spanish word 'arbolito' meaning 'small tree' is formed from two parts: the noun 'árbol' (meaning 'tree') and the diminutive suffix '-ito'. The base word 'árbol' comes from Latin 'arbor', also meaning 'tree'. When the diminutive suffix '-ito' is added to 'árbol', it creates the meaning of a small or cute tree.

The most obvious related Spanish word is 'árbol' (tree), which is the base word from which 'arbolito' is derived. Other common related words include 'arboleda' (grove of trees), 'arbolado' (wooded area), and 'arbóreo' (arboreal). All these words share the same Latin root 'arbor' and relate to trees in different ways.

In English, several scientific or formal words are related to the same Latin root 'arbor': 'arboreal' (relating to trees), 'arboretum' (a botanical garden focused on trees), and 'arbor' itself, which can refer to a garden structure or bower. The Latin 'arbor' has maintained its tree-related meaning across both language families.