a.

1. 群居性的
   The elephant is a gregarious animal.

   大象是一种喜欢群居的动物。

2. 丛生的
3. 合群的；好社交的，爱交际的
   She is the most gregarious girl in our class, and almost all the male students know about her.

   她是我们班上最爱交际的女孩，所有的男生都认识她。

adj.

1. fond of company; sociable.
2. (of animals) living in flocks or colonies.
3. (of plants) growing in clusters.