What's the meaning of "large hug" in definition of "bearhug"?
It implies they are larger than you, but "enthusiastic" can imply the length of time. The hugger doesn't necessarily have to be bear-like, but it definitely helps.
"Large hug" here is the same as in "big hug". "Big" has the meaning of "enthusiastic", so, a "large hug" is an enthusiastic hug.
(informal, with on) Enthusiastic