conceivable(capable of being conceived or imagined; possible; credible; thinkable) adjective [UK: kən.ˈsiː.vəb.l̩] [US: kən.ˈsiː.vəb.l̩]
imaginable(able to be imagined; conceivable) adjective [UK: ɪ.ˈmæ.dʒɪ.nəb.l̩] [US: ˌɪ.ˈmæ.dʒə.nəb.l̩]Killing people while they pray is the most ignoble thing imaginable. = Matar gente mientras rezan es la cosa más innoble imaginable.
inimaginableadjective
unimaginable(unable to be imagined) adjective [UK: ˌʌ.nɪ.ˈmæ.dʒɪ.nəb.l̩] [US: ˌʌ.nə.ˈmæ.dʒə.nəb.l̩]The size of the universe is unimaginable. = La inmensidad del universo es inimaginable.