In the history of science, the symbol “θ∆ics” was James Maxwell, William Thomson, and Peter Tait’s personal communication shorthand symbol for thermodynamics. [1] In his letters, Kelvin, in particular, used phrases such as “2nd law of θΔ” or “2nd law of θΔcs”, among others. [2] The three of them likely used the symbol as a combination sound representation of thermo-dynam-ics, i.e. "theta-delta-ics", in association with the symbol delta "∆" having had a long history in science as the symbol of heat or fire. [3]

In the early phases of the development of the science of thermodynamics, from the 1840s into the early 20th century, aside from θ∆ics, thermodynamics went by such names as "energetics", "mechanical theory of heat", or "theory of heat" among others. In modern use, θ∆ics is the symbol for the Institute of Human Thermodynamics and is used as the bottom page icon for the Encyclopedia of Human Thermodynamics.

The symbol is used in the logo of the SklogWiki (in conjuction with S = K ln W) as shown adjacent. [4]

Human thermodynamics
In extrapolation, in respect to the science of human thermodynamics, knowing that Mars "♂" and Venus "♀" symbol symbolically represent man and woman, respectively, and knowing that the triple parallel line symbol "≡" is a representation of bonding between molecules, such as between human molecules, then the symbolic representation shorthand for human thermodynamics may be: Human (♂≡♀) Thermodynamics (θΔics) or "♂≡♀ θΔics"

References
1. Mahon, Basil. (2003). The Man Who Changed Everything - the Life and Science of James Clerk Maxwell, (pg. 132). UK: Wiley.
2. Maxwell, James. (1876). “Letter to Peter Guthrie Tait”, Oct. 13.
3. Opsopaus, John. (1998). “The Ancient Greek Esoteric Doctrine of the Elements: Fire”, University of Tennessee.
4. SklogWiki (About) - a Statistical Mechanics and Thermodynamics Wiki.