obsession
noun
ob·ses·sion
| \ äb-ˈse-shən
, əb-\
, əb-\
Definition of obsession
1
: a persistent disturbing preoccupation with an often unreasonable idea or feeling
broadly
: compelling motivation
an obsession with profits has an obsession with gambling
2
: something that causes an obsession
Losing weight can be an obsession that results in the avoidance of certain foods.