The Spanish word 'modorra', meaning 'drowsiness' or 'lethargy', has an interesting etymology that traces back to both Latin and Basque roots. It comes directly from the Basque word 'modorro', which originally referred to a truncated tree or trunk. This Basque term itself appears to have been influenced by two sources: the Latin word 'mutilus' meaning 'mutilated' or 'truncated', and the Basque word 'mutur' meaning 'angry'. The semantic evolution from a truncated tree to drowsiness might be explained by the metaphorical connection between the dull, inactive state of a tree trunk and the sluggish, inactive state of drowsiness.

In Spanish, you might encounter related words like 'modorro' (meaning 'dull' or 'stupid') and 'modorrear' (meaning 'to be drowsy'). These words share the same Basque root and maintain similar connotations of dullness or sluggishness.

While there aren't direct English cognates from this specific etymology, the Latin word 'mutilus' that influenced the Basque 'modorro' is related to the English word 'mutilate'. This connection helps illustrate how the original concept of something being cut off or truncated evolved differently in various languages.