The Spanish word 'piño' comes from French 'pignon' meaning 'gear tooth', which itself is related to the French word 'peigne' meaning 'comb'. The connection between these words makes intuitive sense, as both combs and gears have a series of tooth-like projections. In colloquial Spanish, 'piño' has come to refer to a tooth in general, likely due to the visual similarity between teeth, comb teeth, and gear teeth.

While 'piño' is itself a colloquial term, the more common Spanish word for tooth is 'diente'. However, you might encounter 'piño' in casual conversation, particularly in some Latin American countries.

The English word 'pinion', meaning a small gear wheel or a gear with a small number of teeth, comes from the same French word 'pignon'. This connection helps remember that 'piño' is related to tooth-like structures. Additionally, while not directly related, the English word 'pine' (as in pine cone) shares a distant connection, as pine cones were seen as resembling the teeth of a comb.