In the Unknown origin, Truly means "Truly \t-ru-ly\ as a girl's name is a variant of Truth. See for origin and meaning of Truly.
The baby name Truly sounds like Truley and Trule. Other similar baby names are Trudy, Arly, Arely, Drucy, Trudi, Trude, Tilly, Tally, Tula, Tracy, Trilby, Trudey, Truda and Tully."
