♂

The circle and arrow represent the shield and spear, respectively, of the Ancient Roman god of war Mars. Previously the spear had crossed in front of the shield, and the ancient form lacked the shield altogether.[1]

♂︎

Medieval form of the symbol, with the spear crossing the shield

1. (biology) male
   • 1961 August 17, New Scientist, volume 11, number 248 (in English), Reed Business Information, ISSN 0262-4079, page 413:

     In his Mantissa Plantarum (1767) and Mantissa Plantarum altera (1771), [Linnaeus] regularly used ♂, ♀ and ☿ for male, female and hermaphrodite flowers respectively.

   • 1990, Charles S. Churcher, “Cranial Appendages of Giraffoidea”, George A. Bubenik, Anthony B. Bubenik, Horns, Pronghorns, and Antlers: Evolution, Morphology, Physiology, and Social Significance, New York: Springer-Verlag, →ISBN, chapter 1.5, page 183:

     Figure 2. Ossicones, secondary ossification, and sinuses of Giraffa: A Lateral aspect of skull showing courses of veins, areas of dense ossification (heavily stippled) and lesser secondary ossification (lightly stippled), and outlines of skull roofs of male (♂) and female (♀) adults. (After Spinage 1968b.)

   • 2015 July 6, Andy Burns, “Re: C4 last leg”, in uk.tech.broadcast, Usenet‎ (in English):

     I was quite surprised that a few of my friends found the male ♂ (mars) and female ♀ (venus) symbols on toilets in pubs/bars confusing ...

2. (botany, of a flower) staminate
3. (astronomy, astrology) Mars
4. (alchemy, archaic) iron
5. (botany, obsolete) biennial (the orbital period of Mars is 2 years)[2]
6. (rare) Tuesday (refers to the Latin phrase dies Martis, which literally means "Mars's day")

• (biology): ♀

• 🜜, 🜝 iron ore
• 🜡 copper–iron ore
• ⚣
• ⚤‎

From Japanese memes in the Gachimuchi fandom where the sign is placed between or after words to indicate erotic or homosexual things, usually for humorous effect.

♂

1. (biology) male
2. (Internet slang, humorous) Added between two characters of a word or after a word to indicate its relation to homosexual. And derivedly, added to indicate a word's relation to sex.

   哲♂學／哲♂学  ―  zhé ♂ xué  ―  homosexual (without the symbol: philosophy)

   交♂易  ―  jiāo ♂ yì  ―  sexual intercourse (without the symbol: exchange)

For sense 2, associated with the Yaranaika and Gachimuchi memes at Nico Nico Douga, as it was originally added after sexual moaning.

♂

1. (biology) male
2. (Internet slang, humorous) Added between two characters of a word or after a word to indicate its relation to homosexual. And derivedly, added to indicate a word's relation to sex.

   哲 ♂ 学 (tetsugaku; "philosophy", a humorous and misleading tag in Nico Nico Douga to trick viewers into watching Gachimuchi videos)

• Chinese: ♂ (online slang)

• ♀ (♀) (female)
• 発展(はってん) (hatten) (often written as "810"; "development, cruising, looking for sexual partners")