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Hawker's Poor Man's Concordance And Dictionary [1]

We find this word before two of the Psalms, ( Psalms 6:1-10; Psa 12:1-8)! and it is used  1 Chronicles 15:21. And in the margin of our old Bibles, in this chapter of the Chronicles where it is said on the Sheminith to excel, it is rendered on the eighth to oversee. Hence some have supposed that it meaneth an instrument of eight strings. But this is by no means satisfactory; it is too trifling to suppose that the blessed and precious truths of the Psalms were composed for the purpose of mere musical instruments. Those Psalms beyond all doubt have an eye to Christ, and express sweet leading features of his office-character as Messiah. If therefore we suppose (and which I venture to think may be done without violence) that the blessed things contained in them refer to Christ, may we not suppose also that the Psalm itself is therefore dedicated to him? If the reader wishes to see yet farther the foundation of such probable conclusions, I refer him to Parkhurst's Lexicon, page 696, or Fenwick on Titles of the Psalms, page 18. See Musician

Fausset's Bible Dictionary [2]

Psalm 6 and Psalm 12's title. Feminine of Shemini , "the eighth" ( Exodus 22:32);  1 Chronicles 15:21, "the singers were appointed with harps on the sheminith to excel," or "oversee." Gesenius explains, the lowest of the three keys of the human voice, an octave or eighth below the treble; the bass sung by men; as "on alamoth" answers to the treble or female voice, as Alamoth means. Hengstenberg takes it as indicating the time measured according to the number eight. Septuagint and Vulgate translated "concerning" or "for the eighth."

Morrish Bible Dictionary [3]

A Hebrew word in the headings of  Psalm 6 and   Psalm 12 , and in  1 Chronicles 15:21 . It will be seen that in the margin these passages read 'on the eighth,' with which the LXX agrees. It was probably an instrument of eight strings (from shemoneh, 'eight'). Gesenius says it means 'octave'; hence the lowest notes of the scale, and sung by men.

Smith's Bible Dictionary [4]

Shem'inith. (Eighth). A musical term found in the title of  Psalms 6:1. A similar direction is found in the title of  Psalms 12:1. Compare  1 Chronicles 15:21. It seems most probable that Sheminith denotes a certain air known as the eighth, or a certain key in which the psalm was to be sung.

American Tract Society Bible Dictionary [5]

In the titles of  Psalm 6:1-10;  12:1-8 , and in  1 Chronicles 15:21 . It means properly the eighth, and seems to have been not an instrument, but a part in music, perhaps the lowest.

Holman Bible Dictionary [6]

 Psalm 6:1 Psalm 12:1  1 Chronicles 15:21 1 Chronicles 15:20

Easton's Bible Dictionary [7]

 1 Chronicles 15:21 Psalm 6 12

Hastings' Dictionary of the Bible [8]

SHEMINITH . See art. Psalms, p. 772 a .

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [9]

(Heb. with the art. hash-Sheminith', הִשְּׁמַינַית , fem. sing. of שַׁמַינַי , eighth.) The title of Psalms 6 contains a direction to the leader of the stringed instruments of the Temple choir concerning the manner in which the psalm was to be sung. "To the chief musician on Neginoth upon Sheminith" or "the eighth," as the margin of the A.V. has it, and as the same word is elsewhere rendered ( Leviticus 25:32, etc.). A similar direction is found in the title of Psalms 12. The Sept. in both passages renders Ὑπὲρ Τῆς Ὀγδόης , and the Vulg. Pro Octava. The Geneva Version gives "upon the eighth tune." Referring to  1 Chronicles 15:21, we find that certain Levites were appointed by David to play "with harps on the Sheminith," which the Vulgate renders as above, and the Sept. by Ἀμασενίθ , which is merely a corruption of the Hebrew. The Geneva version explains in the margin "which was the eighth tune, over the which he that was the most excellent had charge." As we know nothing whatever of the music of the Hebrews, all conjectures as to the meaning of their musical terms are necessarily vague and contradictory.

With respect to Sheminith, most Rabbinical writers, as Rashi and Aben-Ezra, follow the Targum on the Psalms in regarding it as a harp with eight strings; but this has no foundation, and depends upon a misconstruction of  1 Chronicles 15:21. Gesenius (Thesaur. s.v. נצח ) says it denotes the Bass, in opposition to Alamoth ( 1 Chronicles 15:20), which signifies the Treble. But as the meaning of Alamoth itself is very obscure, we cannot make use of it for determining the meaning of a term which, though distinct from, is not necessarily contrasted with it. Others, with the author of Shilte Haggibborim, interpret "the Sheminith " as the Octive ; but there is no evidence that the ancient Hebrews were acquainted with the octave as understood by ourselves so comparing the manner in which the word occurs in the titles of the two psalms already mentioned with the position of the terms Aijeleth Shahar, Jonath-elem-rechokim, etc., in other psalms, which are generally regarded as indicating the melody to be employed by the singers, it seems probable that Sheminlith is of the same kind, and denotes a certain air known as the eighth, or a certain key in which the psalm was to be sung. Maurer ( Comm. In Psalms 6 ) regards Sheminith as an instrument of deep tone like the violoncello, while Alamoth he compares with the violin; and such, also, appears to be the view taken by Junius and Tremellius. (See Psalms).