What ̽ means
Append it after the vowel it modifies.
In Unicode text, the vowel comes first and the over-cross second: e + ̽ forms e̽. Read the result as one vowel with a pronunciation detail; the combining mark does not create another syllable.
Why does x above sit over i?
It follows i in the text but is drawn above it.
The dot on i gives fonts a choice: some let the over-cross replace the dot, while others place it above the dot. The shape can vary without changing the transcribed vowel.
If the mark appears alone, its vowel may be missing or the app may not know how to position it. Check the vowel-plus-mark sequence in a font that supports IPA.
Specialist phonetics: in an IPA transcription, this mark adds a precise detail about vowel quality.
Read it with the vowel before it; alone, it has nothing to modify.
Don't confuse it with
2Questions people ask
1Why does ̽ show as a box on some devices?
Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.
How to type ̽
̽\033DCodes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.