The Spanish word 'púa' meaning 'spike' or 'thorn' traces back to the Latin language. It originated from the Vulgar Latin word '*pugia' meaning 'sharp point', which itself came from the Latin word 'pugio' meaning 'dagger'. Going even further back, 'pugio' derived from the Latin verb 'pungere', meaning 'to prick' or 'to sting'. You can see how the meaning evolved from an action (pricking), to a weapon (dagger), to a general sharp point, and finally to the modern Spanish word for a spike or thorn.

The Spanish word 'punzar' (to prick or pierce) and 'puntiagudo' (pointed, sharp) share the same Latin root 'pungere'. These words maintain the basic concept of something sharp or piercing, making them semantically related to 'púa'.

Several English words share this Latin ancestry, including 'pungent' (sharp or strong-smelling) and 'puncture' (to pierce or make a hole), both from Latin 'pungere'. While 'pungent' developed to describe a sharp sensation specifically related to smell or taste, and 'puncture' maintained the physical piercing meaning, they all share the core concept of something sharp or penetrating.