English speakers really do believe that INCONCEIVABLE is a form of word CONCEVE, however it is not. They are independent words made of the same morpheme. English is an analytic language with a few synthetic constructions: play - played-playing-plays (forms of verb), forest - forests (plural/singular of noun), he-his-him (genetive and dative forms of personal pronouns). In these examples play and played are dorms of the same word, unlike inconceivable and conceive. In English, adjectives do not have forms, unlike in Japanes or Russian. In japanese adjectives can be positive and negative, present and past and have other forms too. For example: This book is red = Kono hon wa akai. This book was red = Kono hon wa akatta desu. This book was not red = Kono hon wa akakunakatta. Here akai, akatta and akakunakatta are just three forms of the adjective AKAI = red. And there are even more forms, while in English you have only the form RED, regardless how many words you have with that morpheme (redness is AKASA in Japanese which is not considered a form of AKAI, it is an independent word). In Russian, for example, adjectives usually have 24 forms (some of them are repititive). For example: I have a RED book = U men'a est' KRASNAJA kniga. I have a RED pencil = U men'a est' KRASNYJ karandash. I have RED pencils = U men'a est' KRASNYJE karandashi. I write with a RED pencil = Ya pishu KRASNYM karandashom. I write with a RED pen = Ya pishu KRASNOJ ruchkoj and so on, and so forth. And we are discussing only adjectives which don't need to have a lot of forms. What about verbs? They have about amhundred of forms. I will give an example: English: I write, you write, he writes, we write, you write, they write. Russian: ya pishu, ty pishesh', on pishet, my pishem, vy pishet'e, oni pishut. Infinitive PISAT'. Some forms: Pisavshij, napisavshi - all are forms of one word. However PISATEL' (author) with the same morpheme is not a form of the word PISAT', it is an independent word, like INCONCEIVBLE and CONCEIVE.