Dictionary.com
Thesaurus.com

amigo vs. amiga

[uh-mee-goh, ah-mee-, ah-mee-gaw] / əˈmi goʊ, ɑˈmi-, ɑˈmi gɔ /

noun

plural

amigos
  1. a friend, especially a male friend.

[uh-mee-guh, ah-mee-, ah-mee-gah] / əˈmi gə, ɑˈmi-, ɑˈmi gɑ /

noun

plural

amigas
  1. a female friend.