勃起

1. Origins, structure, and basic meaning

• Structure: In 勃起 (ぼっき), rising 勃 and arising 起 combine in the physiological term erection.
• Basic usage: 勃起 is a medical or neutral noun for the physiological erection of bodily tissue.

2. Common pitfalls and similar expressions

• A physiological term
  • It should not be broadened to emotional excitement or the ordinary protrusion of an object.