≍ means equivalent to, in math and logic. You've perhaps seen the meaning written just as a tilde "~" such in ASCII-based text, or written as "==" in JavaScrip

≍ means equivalent to, in math and logic. You've perhaps seen the meaning written just as a tilde "~" such in ASCII-based text, or written as "==" in JavaScript meaning loosely equal to. IIRC the symbol is also useful for asymptotes and limits, such as Big O notations.