Translation:A big shoe
WHy do they always want an article? "Big shoe" should work fine.
why not the big shoe
Why is it not chikubwa?
because 'kiatu' is in the noun class 'ki/vi'. There is no noun class with the prefix 'chi-'
As given by the notes for the Adjective lesson:
The Ki-/Vi- class takes the ki- concord before a consonant in singular. The ch- is only used before vowels in singular.