Conceptual Development: Some similar names appeared in The Etymologies from the 1930s: N. Orchelanath and (rejected) Orchallamath (EtyAC/KHAL², MBAT(H)).
masculine name. *Tall Lord
Word Gloss orchal “tall, tall; [N.] superior, eminent, lofty” -dor “*king, lord”
Orchaldor's name is Sindarin and appears to mean "Eminent Man" (from the word orchal, 'superior', and the masculine suffix -dor).