This is the 5566th most frequent Korean word.
무선
Wireless.
Here, 무선 (wireless) serves as an adjective describing 인터넷 (internet), collectively forming 'wireless internet'.
무선 인터넷은 편리합니다.
Wireless internet is convenient.
In this context, 무선 is again an adjective modifying 이어폰 (earphones), creating the term 'wireless earphones'.
나는 무선 이어폰을 사용합니다.
I use wireless earphones.
The word '무선' functions as an adjective for 장치 (devices) to indicate they are 'wireless devices'.