The Spanish word 'peligroso' (meaning 'dangerous') comes from the Latin word 'periculosus', which also meant 'dangerous'. The Latin word was formed by combining 'periculum' (meaning 'danger, risk') with the suffix '-osus' (meaning 'full of'). As Latin evolved into Spanish, 'periculum' became 'peligro' and the suffix '-osus' became '-oso', naturally combining to form 'peligroso' - literally meaning 'full of danger'.

The simpler and more common Spanish word 'peligro' (meaning 'danger') is directly related to 'peligroso', as it comes from the same Latin root 'periculum'. Understanding this connection can help you remember that 'peligroso' is essentially describing something that is 'full of peligro (danger)'. The '-oso' ending in Spanish, like in 'peligroso', is a common suffix used to create adjectives meaning 'full of' or 'characterized by' something.

While English doesn't have any direct descendants from Latin 'periculum', we do have several related words that entered English through French, such as 'peril' (danger) and 'perilous' (dangerous). These words share the same Latin ancestor as 'peligroso'. You can see how 'perilous' and 'peligroso' are similar both in meaning and in their historical formation - both essentially meaning 'full of danger'.