The LOOKUP function in Excel is used to search one column of data and find data in the corresponding row. For example, if you are searching a column of employee IDs the LOOKUP function can find, say, employee number 12345 in the ID column. Once it has found the ID 12345 it then can return data from that same row.
Lookup - searching for a specified value in a table of data.
Lookup value - a value to search for.
Return value (matching value or match) - a value at the same position as the lookup value but in another column or row (depending on whether you do vertical or horizontal lookup).
Lookup table.