What is the term for a secondary or suggested meaning of a word? (apex)

Apex is defined as the tip of a summit or the climax of something or someone. It could also be called "the turning point or pivotal". If used in a sentence, it could be: The apex of her life happened when she graduated college – shifting from a mere college student to a worker in the society.

to save the day, harry must get past a scary three-headed guard dog.

the sentence that avoid faulty coordination is:

culture, which is well represented in philadelphia, plays a major role including theatre, music, and the visual arts.  

faulty coordination occurs when the writer gives equal importance two different ideas (clauses) which in fact are not equivalent. in order to correct a misplaced clause or idea, the writer can place less important or emphatic ideas in a relative clause as in the previous sentence.