multi arm ()
A character with more than the usual number of arms for that species. In most species, the usual is 2.
As a general rule, the multi/multiple tags will tend to mean either "more than normal compared to humans" (8 nipples, 2 heads) or "more than normal for that species" (a horse with 6 legs). Invented species and genitalia are probably the most common exceptions. Use your best judgement when tagging this.