lack ‧ a ‧ dai ‧ si ‧ cal /ˌlækəˈdeɪzɪk ə l◂/ BrE AmE adjective
[ Date: 1700-1800 ; Origin: lackaday expression of sadness (17-19 centuries) , from alack the day ]
not showing enough interest in something or not putting enough effort into it:
David has a rather lackadaisical approach to his work.