Main Entry: 1soph·o·more
Pronunciation: 'säf-"mOr, -"mor also 'sof- or 'sä-f&- or 'so-f&-
Function: noun
Etymology: perhaps from Greek sophos wise + mOros foolish
Date: 1688
: a student in the second year at college or a 4-year secondary school
It is a term referring to the second year in a 4-year school. Therefore, the second album is a "sophomore" album.
The word "sophomoric" means literally, "wise fool" because people of that educational level have learned enough to be considered wise, but tend to be foolish in their inflated opinion of themselves.