Strange, curious (5)
I believe the answer is:
queer
I believe this is a double definition.
'strange' is the first definition.
(synonyms)
'curious' is the second definition.
(I know that curious can be written as queer)
(Other definitions for queer that I've seen before include "Unusual" , "Strange, curious" , "Strange, odd" , "Peculiar" , "Eccentric" .)