Bi-curious is a term used to refer to people of a heterosexual or homosexual identity who, while showing some curiosity for a relationship or sexual activity with a person of the sex they do not favor, distinguish themselves from the bisexual label. The term is sometimes used to describe a broad continuum of sexual orientation between heterosexuality and bisexuality. The terms heteroflexible and homoflexible are also applied to bi-curiosity, though some authors distinguish heteroflexibility as lacking the "wish to experiment with ... sexuality" implied by the bi-curious label.
The term bi-curious implies that the individual has either no or limited homosexual experience in the case of "heterosexual" individuals or no or limited heterosexual experience in the case of "homosexuals", but may continue to self-identify as bi-curious if they do not feel they have adequately explored these feelings, or if they do not wish to identify as bisexual.
A heterosexual or homosexual who engages in bisexual activity during a three-way/threesome/ménage-à-trois, 3-on-2, or other group sex is known as a vortex bisexual. This is a group to whom the term switch hitter may be accurately applied; other slang terms such as AC/DC, ambisexterous, versatile etc. are reserved to denote a stronger form of bisexuality.
Someone with sexual experience who is experimenting with activities with the other gender (normally during puberty) with whom they generally have not had relations may or may not be termed bi-curious, to the degree of that experimentation satisfying the person's general curiosity. In general, the term refers to someone who is contemplating and has prepared oneself for, but not yet acted upon - relations with those of same and different sex.