Miscellaneous
There are a few more terms and flags that I couldn't quite fit into another category, and making them their own category would be a very short page.
Pan-
Pansexual/panromantic means to be attracted to people regardless of their gender. Some also choose to define it as being attracted to all genders, much like being omnisexual/omniromantic.
The flag was created in 2010 by someone named Jasper (JustAJasper on Tumblr, ShrikeAbyssals on Twitter), created anonymously at the time. The flag was first and foremost designed to be visually appealing to Jasper, stating all the flag proposals at the time were ugly and inconsistent with other communities pride flags. The pink represents feminine people, the yellow nonbinary people, and the cyan maculine people.
Poly-
Polysexual/polyromantic means to be attracted to more than one gender. While bisexual/biromantic also has a similar meaning, it is presumed to mean attraction to the 2 binary genders (Bisexual can and has historically meant that, but that definition does not apply to all bi people).
The flag was designed by someone named Samlin in 2012, submitted to the Tumblr blog FuckYeahPolysexuality (though I found a Tumblr blog of the name Samlin, I could not confirm if this was the same individual who submitted the flag). Samlin made it similar to the pan and bi flags as they all fall under the multisexual spectrum. Though they did not give meaning to the colors, they are often interpreted to represent the following: pink for attraction to women, green for attraction to nonbinary people, and blue for attraction to men.
Omni-
Omnisexual/omniromantic is an orientation that describes someone with attraction towards two or more genders. While pan people might factor gender into their attraction, to be omni means it explicitly does.
The flag was designed by PastelRoswell on Tumblr (previous username PastelMemer) and posted to pride-color-schemes in 2016. The flag was meant to be similar to the bi flag but with more color variety, and the colors were moreso meant to compliment each other than have meaning. The only color given meaning is the dark stripe in the middle, representing, "the infinite potential depth and complexity of an identity where all genders are attractive in individual ways."
Polyamorous
To be polyamorous, or polyam, is to desire having more than one partner at once, or being capable of loving more than one person at a time. It can also refer to a consentual relationship where a person is involved romantically and/or sexually with more than one person at once.
The flag was created by Jim Evans in 1995. The blue represents openness and honesty, red love and passion, black solidarity with those who must hide their polyamory, and the gold pi the values to emotional attachments poly people hold. The letter pi was used for the first letter in polyamory. Evans also mentioned the community has a history of using Greek letters, such as lambda, and wanted to evoke solidarity in that, as well as wanting pi to be used as a subtle way to indicate to others that they were polyamorous. There have been several proposals for redesigns of this flag, but this is still as of now the most widely recognized design.
Sapphic
Sapphic is a term to refer to women and woman-aligned people who are attracted to women and women-aligned people, but not necessarily exclusively to them. This term includes women and nonbinary people who are lesbian, bi, pan, polysexual/polyromantic, omni, or may otherwise be attracted to other genders.
The sapphic flag was designed by tumblr user lesbeux-moved in 2015, originally having a realistic image of violets in the center of the flag. The simplified violet was added by Mod Hermy of pride-color-schemes. The pink represents love, and the violet flower was historically used to denote sapphic love.
Achillean
Achillean is a term to refer to men and men-aligned people who are attracted to men and men-aligned people, not necessarily exclusively to them.This term includes men and nonbinary people who are gay, bi, pan, polysexual/polyromantic, omni, or may otherwise be attracted to other genders.
The achillean flag was designed by tumblr user PrideNPositivity in 2016, originally having a realistic image of a green carnation in the center of the flag. The simplified carnation was added by pride-color-schemes on Tumblr. The blue represents joy, and the green carnation was historically used to subtly hint that a man was gay.
Bear
Bear is a subculture of achillean men who portray stereotypical "rugged masculinity". Bears are typically over 30, plus size, and have a lot of body hair, including beards. The subculture was founded sometime in the mid-1980s.
The International Bear Brotherhood flag was created by Craig Byrnes in 1995. The colors of the flag represent fur, or body hair, and how it comes in a diverse array of colors. The bear paw in the top left is an indicator of the cultures association with the animal.
Leather
Leather is a sexual subculture centered around wearing leather garments, whether it be leather jackets or leather harnesses. Leather is not inherently BDSM, despite the common association. It has existed since the late 1940s, likely stemming from post-WWII biker culture. The leather community is largely comprised of gay men, thus its associations with the LGBTQIA community.
The leather pride flag was designed by Tony DeBlase, introduced to the community at the International Mister Leather conference in 1989. He leaves the meanings of the colors and symbols up to the interpretation of viewers.