The antonyms or opposites of the word "unavailable" include "available," "accessible," "contactable," "responsive," "attainable," and "obtainable." When something is available, it means that it is ready, present, or within reach. On the other hand, when something is inaccessible or unattainable, it means that it cannot be reached or approached. Contactable refers to the ability to be reached through various means of communication such as phone or email. Responsive refers to the ability to provide a prompt and satisfactory response. Obtaining something means acquiring or getting hold of it. By knowing the antonyms of 'unavailable,' one can communicate effectively and convey the message more accurately.