The Spanish word 'sustantivo' (meaning 'noun') comes from the Latin word 'substantivus'. This Latin word was formed by combining several elements: 'sub-' meaning 'under', 'stare' meaning 'to stand', the agent suffix '-nt-', and '-ivus' meaning 'relating to'. The literal sense was something like 'relating to what stands under or exists independently', which evolved to refer to nouns as the part of speech that names independent things, people, or concepts.

Some related Spanish words include 'sustancia' (substance), which shares the same Latin roots of 'sub-' (under) and 'stare' (to stand), literally referring to what 'stands beneath' or exists. Another related word is 'estar' (to be, to stay), which comes from Latin 'stare' and shares the basic concept of standing or existing.

English speakers can connect 'sustantivo' with several familiar English words. 'Substantive' is a direct cognate, meaning 'having independent existence or function.' The word 'substance' is also related, coming from the same Latin elements meaning 'standing under.' Even the common English verb 'stand' is distantly related, as it shares ancient roots with Latin 'stare'.