almidonar

To starch fabric — shirts, collars, tablecloths — a laundry-specific verb (almidonar el cuello de la camisa) that also gives Spanish the adjective almidonado, used figuratively for a stiff, overly formal or unbending personality.

• La lavandera almidonaba los cuellos de las camisas a mano. — The laundress starched the shirt collars by hand.
• Prefiero no almidonar tanto la ropa, queda demasiado rígida. — I prefer not to starch the clothes so much, it comes out too stiff.
• Es un hombre almidonado, siempre formal y sin soltarse nunca. — He's a stiff, buttoned-up man, always formal and never letting loose.

Missing the figurative use of almidonado for a person — it's a natural, common way to describe someone rigid or overly formal, not just a laundry term.