Fetish disorder is a strong sexual attraction either to inanimate objects or to parts of the body that are not traditionally seen as sexual. The term "fetishism" comes from the Portuguese word feitico, which means "fixed fascination". 

Fetishism falls into the general category of paraphilic disorders, a term which refers to the great sexual attraction to any object or person outside of genital stimulation.

Such people can be "obsessed" with objects such as underwear or high-heeled shoes, as well as body parts such as feet. The individual can get sexual pleasure only through the use of this object or by focusing on that part of the body.

Fetish disorder is a much more common occurrence in men than in women and even many sources say it occurs exclusively in men.

When is it disturbing?

Fetishisms become a problem when they interfere with the development of a normal social and sexual life or when sexual arousal becomes impossible without the "fetish" object. Therapists and sex and relationship therapists can help.

Source: Psychology Today