The Spanish verb 'poder' (meaning 'to be able' or 'can') comes from Vulgar Latin '*potere', which developed from Classical Latin 'posse' meaning 'to be able'. The Latin 'posse' itself was formed by combining two elements: 'potis' meaning 'able, capable' and 'esse' meaning 'to be'. This combination literally meant 'to be able' and evolved through sound changes to become the modern Spanish 'poder'.

The development from Latin 'posse' to Spanish 'poder' shows a common pattern where the infinitive ending changed (-ere), and the stem underwent consonant changes (t > d) that are typical in the evolution from Latin to Spanish.

Several common Spanish words are related to 'poder', including the noun 'el poder' meaning 'power', 'poderoso' meaning 'powerful', and 'potente' meaning 'potent, powerful'. These all share the same Latin root emphasizing ability and capability.

English speakers can connect 'poder' to several familiar words that come from the same Latin root, such as 'potent', 'potential', and 'possible' (from Latin 'possibilis', derived from 'posse'). The word 'power' itself, though it came through French, is ultimately related to the same Latin root 'potis'. Understanding these connections can help remember that 'poder' relates to ability and power.