Definitions of hostile:

• adjective:   very unfavorable to life or growth

  Example: "A hostile climate"

• adjective:   characterized by enmity or ill will

  Example: "A hostile nation"

• adjective:   impossible to bring into friendly accord

  Example: "Hostile factions"

• adjective:   used of attempts to buy or take control of a business

  Example: "Hostile takeover"

• adjective:   marked by features that oppose constructive treatment or development

  Example: "Not able to accomplish much in such a hostile environment"

• adjective:   very unfriendly

  Example: "A hostile attitude"

• adjective:   not belonging to your own country's forces or those of an ally

  Example: "Hostile naval and air forces"