hashtag
Internet term for a hashtag, used on platforms like Twitter. The cross-reference to ハッシュタグ indicates it is a Japanese equivalent.
See also: ハッシュタグ
You can find related posts with this hashtag.
Let's decide on a hashtag for the event.
ハッシュタグ is the more common loanword for 'hashtag'. 検索目印 is a native Japanese equivalent, less frequent but understandable.
Compound of 検索 (search) and 目印 (mark, sign). Literally 'search mark', coined as a Japanese equivalent for 'hashtag'.