1Especially of language: powerfully and forcibly expressive; spoken with force or emphasis.
2Of an action, attribute, argument, etc.: strongly marked; powerful, forceful.
3Of a person: = "emphatic".
4Of a word, syllable, etc.: that bears the stress in pronunciation. Also of a word: that has particular importance in a sentence.
5Designating colours that are not inherent in an object, such as those produced by a prism or seen in a rainbow, regarded as being less real than colours seen on the surface of something.
In modern use emphatic is the usual word; emphatical was more common until the 18th cent
Mid 16th century (in an earlier sense). From post-classical Latin emphaticus emphatic + -al.