ear tag1
/ˈɪə taɡ/noun
A tag or marker of a durable material which is attached to the ear of an animal to indicate identity, ownership, etc.
Origin
Late 19th century; earliest use found in National Live-stock Journal. From ear + tag.
ear-tag2
/ˈɪətaɡ/verb
[with object] To attach an ear tag to (an animal).
Origin
1920s. From ear tag.