In Psalms there are several words that are unique...most are not used anywhere else in the Bible. Several of these words have obscure meanings - scholars still are not sure of some definitions. Below I have listed these terms along with their meaning (if known), or possible meanings (if unsure).1,2
If you find a word in Psalms that you are unclear of its meaning, and it does not appear in this list; then please email the word to me (email available on my profile). I will look it up and reply to you with its meaning or possible meanings, and add it to this list.
Alamoth - meaning is unsure. Possibly means: (1) a high pitch; (2) a tune for soprano voices; (3) for a women's choir/ensemble. Hebrew root of the word means: (1) young women; (2) virgins.
Asaph - a Gershonite Levite choir leader in the time of David and Soloman - see 1 Chronicles 15:16-19; 16:1-7; 2 Chronicles 5:6,12. Called a seer in 2 Chronicles 29:30. His sons were made musicians - see 1 Chronicles 25:1-9.
Gittith - meaning is unsure. Possibly means: (1) a particular instrument; (2) a musical term; (3) a tune from Gath; (4) a song for the grape harvest.
Higgaion - meaning is unsure. Possibly means: (1) a device denoting a pause in an instrumental interlude; (2) a murmuring harp tone; (3) a deep sound or tone.
Mahalath - meaning is unsure. Possibly means: (1) a song tune; (2) a musical instrument; (3) a dance. May be related to Hebrew word meaning: sickness. Name of one of Esau's wives in Genesis 28:9 (a daughter of Ishmael); and one of Rehoboam's wives in 2 Chronicles 11:18 (King David's granddaughter).
Maskil - (1) to be prudent; (2) to have insight; (3) a contemplative, instructive or wisdom psalm.
Miktam - meaning is unsure. Possibly means: a plaintive style.
Muth-labben - musical term meaning: authority.
Selah - meaning is unsure (also used in Habakkuk 3:3,9,13). Possibly means: (1) a musical notation; (2) pause, or a moment for silence; (3) a signal to fall prostrate in worship; (4) a word those worshipping speak; or (5) forever/eternally true. Related word, "Sela," used in 2 Kings 14:7 to refer to a place in Edom.
Sheminith - musical term meaning: instruments, or directions to use the instrument of eight strings. Also appears in 1 Chronicles 15:21.
Shiggaion - meaning is unsure. Possibly means: (1) a passionate song with rapid changes of rhythm; (2) a dirge; (3) irregular.
Song of Ascents - meaning is unsure. Possibly means: (1) songs pilgrims sang as they traveled the roads going up to worship in Jerusalem; (2) song rising in tone or intensity. Psalms 120-134.
Sons of Asaph - see Asaph above.
Sources:
1 HSCB Bullet Notes. Holman Christian Standard Bible Holman Bible Publishers: Nashville, 2004. pgs. 1057-1062.
2 Biblical Cyclopedic Index. The Open Bible: Expanded Edition Thomas Nelson Publishers: Nashville, 1985. pgs.29-326.