You're unlikely to find "chairman's" in a dictionary. Spell checkers (which at least for languages like English usually use table lookup) often succeed with co

You're unlikely to find "chairman's" in a dictionary. Spell checkers (which at least for languages like English usually use table lookup) often succeed with common apostrophe-s nouns, but fail with less common ones, because even for English it's often considered impractical to store all possible possessive forms. Where dictionary lookup really becomes infeasible is in languages with a great deal of inflectional morphology, like Finnish. For languages like that, you need some kind of morphological analyzer. Hunspell provides a fairly simple one, while a number of finite state transducers (xfst, foma, sfst...) provide more sophisticated mechanisms to build a morphological parser with.