What is the meaning of Þ?

a voiceless dental fricative (IPA: θ).

romanization of 𐌸

The thirtieth letter of the Icelandic alphabet, written in the Latin script.

A letter of the Middle English alphabet, representing /θ/ or /ð/; it was gradually replaced by "th".

a letter of the Old English alphabet, representing /θ/, which was pronounced [θ] or [ð]

a letter of the Old Norse alphabet, representing /θ/, which was pronounced [θ] or [ð]

a letter of the Old Swedish alphabet, written in the Latin script.

Source: wiktionary.org