Coalesce

coalesce [ koh-uh'-LES ]
[ intransitive verb ]

MEANING :
1. (intr. v.) to combine to form one unit
2. (intr. v.) to blend or unify
3. (intr. v.) to merge or amalgamate

USAGE EXAMPLE 1 :
Three political parties could coalesce to form the government as none of them were able to achieve a majority independently.

USAGE EXAMPLE 2 :
These particles may help water droplets to coalesce, and so aid the formation of clouds.