Past tense of 'grandstand'; to perform showy or dramatic actions to impress an audience, often prioritizing appearance over substance.
From 'grandstand' (the raised seating structure at sporting events where the best view is had), the verb meaning to perform ostentatiously as if playing to that audience. Became common in late 19th/early 20th century American English.
The verb 'grandstand' is pure American—it originally meant to play a game in a showy way to impress spectators, and it captured the theatrical, exaggerated style of early baseball players who were showing off for the crowd!
Complete word intelligence in one call. Free tier — 50 lookups/day.