What is the meaning of the word "ear"?

Definitions:

In agriculture, refers to the grain-bearing part of a cereal plant, such as corn or wheat. NOUN
- The farmer inspected the ears of corn to determine if they were ready for harvest.
In sailing, refers to a rope or line attached to the head of a sail to hold it in place. NOUN
- The sailor adjusted the tension on the ear to trim the sail for better performance.
Refers to the sense of hearing or the ability to perceive sound through the auditory system. NOUN
- His ear for music allowed him to appreciate the subtle nuances of the symphony.
The organ of hearing and balance in humans and other vertebrates. NOUN
- She gently cleaned her ears with a cotton swab.