2nd or 3rd (7)
I believe the answer is:
ordinal
I believe this is a double definition.
'2nd' is the first definition.
(similar in meaning)
'3rd' is the second definition.
(similar in meaning)
(Other definitions for ordinal that I've seen before include "Of position in series; service book (hist.)" , "First, second, third could be such a numeral" , "Possibly first or second" , "First, second, third etc." , "Relating to position in a sequence" .)