But sometimes an intensive force.

E.g. per-terrere = to thoroughly frighten.

In all such cases you must be partly guided by the context.

(For List of Important Prefixes, see [Appendix II.] pp. 277—281.)

[(3)] Suffixes (other than grammatical inflexions).

A knowledge of the most important suffixes will often help you to the correct meaning of a Latin word, the root of which is familiar to you.

Thus from the √ag = drive, move, we have—

by addition of-tor(= agent or doer of an action), actor = a doer, agent.
„„„-men(= acts or results of acts), agmen = a course, line of march, &c.
„„„-ilis(= belonging to, able to), agilis = easily moved, agile.
„„„-ito(= forcible or repeated action), agito = put in action, agitate.

(For List of Important Suffixes, see [Appendix III.] pp. 282—286.)

[(4)] Cognates, that is, words related in meaning through a common root. You will find it very useful to make for yourself lists of cognate words.