afectar

To affect — to have an impact or influence on something or someone, often negatively: la sequía afectó la cosecha. Also used to mean 'to feign' in a more literary register (afectar indiferencia), a much rarer sense than the everyday 'to impact.'

• El ruido me afecta la concentración. — The noise affects my concentration.
• La crisis afectó a miles de familias. — The crisis affected thousands of families.
• Afectaba una calma que no sentía. — He feigned a calm he didn't feel.

Assuming afectar always carries the rarer 'feign' sense — that older meaning exists but is uncommon; almost always afectar simply means to influence or impact, matching its English cognate's primary meaning.

Often confused with influir.