The glyph is not a composition. Its width in East Asian texts is determined by its context. It can be displayed wide or narrow. In bidirectional text it is written from left to right. When changing direction it is not mirrored. The word that U+03BD forms with similar adjacent characters prevents a line break inside it. The glyph can be confused with one other glyph.
The Wikipedia has the following information about this codepoint:
Nu (; uppercase Ν, lowercase ν; Greek: vιni[ni]) is the thirteenth letter of the Greek alphabet, representing the voiced alveolar nasal IPA:[n]. In the system of Greek numerals it has a value of 50. It is derived from the ancient Phoenician language nun . Its Latin equivalent is N, though the lowercase () resembles the Roman lowercase v.
The name of the letter is written νῦ in Ancient Greek and traditional Modern Greek polytonic orthography, while in Modern Greek it is written νι[ni].
Letters that arose from nu include Roman N and Cyrillic Н.