Long since has 2 different meanings across 1 category:
Adverb
Adverb
1
of the distant or comparatively distant past
"We met once long ago"
"they long ago forsook their nomadic life"
"left for work long ago"
"he has long since given up mountain climbing"
"This name has long since been forgotten"
"lang syne"
2
Long ago; in the (distant) past.
Example Sentences
"We met once long ago"
adverb
"they long ago forsook their nomadic life"
adverb
"left for work long ago"
adverb
"he has long since given up mountain climbing"
adverb
"This name has long since been forgotten"
adverb
"lang syne"
adverb