Heteroflexible or Elasexual is a variant of bisexuality for when one is mostly attracted to the opposite gender, but is also occasionally attracted to the same gender. The opposite, when one is primarily attracted to the same gender and occasionally attracted to the opposite gender, is homoflexible.
Both of these terms are controversial in the Bisexual community, and many view them as biphobic, due to the labels adding to the stereotype that, to be bisexual, you must experience a more or less, if not total, evenly split attraction to at least two genders. This is a common misconception about bisexuality, and is completely erroneous.
Kinsey Scale
The Kinsey Scale is a way to determine one's sexual preferences through a test. Once one takes the test, they will be given a score from 0-6; 0 being exclusively heterosexual, 6 being exclusively homosexual. Individuals who identify as 'heteroflexible' will usually fall at about a 1 on this scale; For the test to report a result that indicates bisexuality, the range of the result must be from 1 to 5.