SUFFIX: able

Did you know that there is a rule for forming adjectives out of verbs by adding the suffix 'able'?

I've found out that, for instance, given the verbs 'read' and 'cry', we can write 'readable', but never 'cryable', and the reason is:

The suffix '-able' can be added to transitive verbs only. What does it mean after all?

When we read, we read 'something', and in this case, once the verb 'to read' requires an object (a direct object), it is of a transitive type. On the other hand, 'to cry' does not play the same role, thus not admitting the suffix 'able'.