ΘΔ - What does ΘΔ mean?

ΘΔ is slang for "Therian." See an example of how people use it.
When you see the symbol ΘΔ in someone's social media bio, it means they are a therian. You might see therians use this symbol on Twitter, TikTok, Instagram, and other platforms, to identify their kinship with an animal.

Synanthrope θΔ on X: For anyone wondering what -> θ∆ these little symbols mean, these are to denote that someone is therian or otherkin! Therians are those who identify as animalistic beings

You never realize how much your community means to you till 」HearthFox🪶 ΘΔ の漫画

🏳️‍⚧️ Carmine but Vore θΔ🏳️‍⚧️ 💛💙 (@HormnyCheese) / X

Therian Poster Child ΘΔ 🔜 TFF (@fahstine) / X

cohost! - @Shima

Va'renkai θΔ Werewolf (@EldritchLycan) / X

SHEATH KEEF👁👁ΘΔ 🏳️‍⚧️🇭🇹🇵🇷 (@scruffiie) / X

Predicted impact of increasing levels of deterrence (θΔ) upon

ATTY ΘΔ Dawg Girl, Beagle Babe (@PeachDoggy) / X