The Spanish verb 'soñar' (to dream) comes from the Latin verb 'somniare', which also meant 'to dream'. 'Somniare' itself was derived from the Latin noun 'somnus' meaning 'sleep'. The evolution from Latin to Spanish saw the 'mn' consonant cluster simplify to 'ñ', a common sound change in Spanish, while maintaining the core meaning of dreaming.

Some related Spanish words include 'sueño' (dream/sleep), 'soñoliento' (sleepy), and 'ensueño' (daydream). All these words share the same Latin root 'somnus' and form a family of words related to sleeping and dreaming in Spanish.

In English, we can find several words that share the same Latin root 'somnus', including 'somnolent' (sleepy, drowsy), 'insomnia' (inability to sleep), and 'somnambulist' (sleepwalker). While these English words tend to focus more on the 'sleep' aspect of the original Latin meaning rather than dreaming, they help demonstrate how the ancient root evolved differently in various languages.