Meldis was the Sindarin name for Zimrahin, which means friend.
Other versions of the legendarium
In the 'Folk of Marach' family tree from The War of the Jewels, Zimrahin and Malach had a third child. Originally (in version one of the table) there was a note for multiple children that said, "Others not concerned in these Chronicles". In version two of the table this became one name, "Sael..th" that was changed to "Saelon", though this was subsequently struck out.