erection

Turgidity in a tissue brought about by distension with blood: usually referring to the enlargement and stiffening of the penis in a state of sexual arousal; also applicable to the clitoris. Given the appropriate stimulus, the arterial blood vessels dilate, blood floods into specialized ‘spongy’ tissue, and the engorgement itself blocks outflow through the compressible veins.

— Stuart Judge

See coitus; ejaculation; impotence; urogenital system.