Melder was the 22nd century term used for Vulcans with the ability to initiate a mind meld.
In the 22nd century, the mind meld was considered an abhorrent practice by the Vulcan High Command and the melders were treated as an unwanted subculture, described as genetic aberrations. They were usually excluded from public service or had to conceal their abilities from the authorities. Both Yuris and Soval were suspended from their government posts once their identity as a melder became public. (ENT: "Stigma", "Awakening")
T'Pol was described as not having the relevant genetic profile, but still initiated a mind meld in "Affliction". It is therefore possible that sufficient training could enable any Vulcan to gain the melder traits.
Untrained melders could also transmit the Pa'nar Syndrome to non-melders. However, a trained melder like T'Pau also could cure this disease. (ENT: "Kir'Shara")