TALE OF TWO SUFFIXES

In English, there are two suffixes which in Spanish both translate the same way, but often mean different things. These are -ic and -cal. In some cases, the difference is very clear.
eg.Hysteric (the noun), Hysterical (the adjective)
But:

Economic vs. Economical


People sometimes describe something as economic when they mean economical. Economic means‘ concerning economics’: he‘s rebuilding a solid economic base for the country’s future.

Economical means‘ thrifty, avoiding waste’: Small cars should be inexpensive to buy and economical to run.

Others:

Historic vs. Historical

1 On the use of an historic moment; or a historic moment;  
2 Historic and historical are used in slightly different ways. Historic means‘ famous or important in history’, as in a historic occasion; , whereas historical means‘ concerning history or historical events’, as in historical evidence; : thus a historic event; is one that was very important, whereas a historical event is something that happened in the past.  

There are still more examples of this, but it’s interesting to note that there is no such word as grammatic, only grammatical.


Geometric vs Geometrical
The Oxford English Dictionary gives Geometrical as a variant of Geometric.

Geometric

|ˌjēəˈmetrik|

adjective 

1 of or relating to geometry, or according to its methods.

2 (of a design) characterized by or decorated with regular lines and shapes : traditional Hopi geometric forms.

American and British Pronunciation here:

http://www.thefreedictionary.com/geometric