means A patent is a legal right granted by a government that lets an inventor stop others from making, using, or selling their invention for a set period, in exchange for publishing how it works; as an adjective it means open or obvious.

from From the Latin 'patere,' meaning 'to lie open,' via the phrase 'litterae patentes' — 'open letters.' These were royal documents granting a right or title, sealed but left unfolded so anyone could read them, as opposed to 'letters close,' which were sealed shut for private eyes. The French shortened this to 'lettre patente,' and English clipped it further to just 'patent.' That same root explains why something blindingly obvious is 'patently' clear — it lies open for all to see.