1) a public meeting at which goods are sold to the person offering the most money (auction)

2) the most basic or simplest parts (basics)

3) the most interesting, intense, violent, energetic etc part (of an event, game, speech, storm etc) (climax)

4) the part (of a problem) that is the most difficult to solve (crux)

5) the most forward part (forefront)

6) the part of a view nearest to the observer; the most noticeable position (foreground)

7) the belief that pleasure is the most important thing in life (hedonism)

8) the most important or chief kind, tendency etc (mainstream)

9) (a particular kind of) matter; the most important part; chief or real meaning of something (substance)

10) the most crowded part; part where there is great activity; having a large extent from one side to the other; having a large number of units close together; full of or packed with something; (of liquids) semi-solid; (of a person) stupid (thick)