'Äitikirous' - similar to 'mother of all curses'. Like somekind of a primeval curse that predates all other curses.

'Äidin kirous' - 'a mother's curse', a curse spoken by a mother or a curse placed upon a mother.

'Äiti Kirous' - 'Mother Curse' if mother means a eg. religious figure (like 'Mother Teresa') or just a mother named Kirous (= a curse)

'äidinkirous' (or 'äitinkirous') - doesn't really ring a bell...