適当 (tekitō) means "suitable," "proper," or "appropriate." You use it when something is just right for a particular situation or purpose. However, be careful, as it can also sometimes mean "random" or "careless" depending on the context. For example, 「適当な服を選んでください。」 (Please choose appropriate clothes.)

ある状況や目的にちょうど良いことを意味します。時々「いい加減な」という意味もあります。「適当な服を選んでください。」