noun
head harness; head strap
A strap or harness worn around the head, often used to secure headgear or equipment. The term is somewhat specialized and not an everyday word.
ヘルメットの頭紐をしっかり締めてください。
Please fasten the helmet's head strap securely.
この帽子には調整可能な頭紐が付いている。
This hat comes with an adjustable head strap.
あご紐 is a chin strap, while 頭紐 is a strap that goes around the head.
ヘッドバンド is a loanword for a headband, often used in sports or fashion, while 頭紐 is more functional and less common.
Compound of 頭 (あたま, 'head') and 紐 (ひも, 'string, cord'). The reading あたまひも is a straightforward combination of the two components.