Boyd’s Bible Dictionary:

(a dumb dove of distant places). Title to, and probably melody of Psalm 56.

Concise Bible Dictionary:

Words signifying “dove of silence in far-off lands,” found only in the title of Psalm 56: its allusion is not known.

Strong’s Dictionary of Hebrew Words:

from 3123 and 482 and the plural of 7350; dove of (the) silence (i.e. dumb Israel) of (i.e. among) distances (i.e. strangers); the title of a ditty (used for a name of its melody)
KJV Usage:
Jonath-elem-rech okim

Jackson’s Dictionary of Scripture Proper Names:

the dove of silence among strangers (literally the dove of silence of distances)

Potts’ Bible Proper Names:

English form of a, Hebrew phrase; meaning, a dumb dove in distant places, Psa. 56: Title.