a. or sb. Astrol. Obs. Also -il. [ad. mod.L. tredecīl-is, f. L. trēs three + dec-em ten; cf. quartile, sextile.] Denoting an aspect, introduced by Kepler, in which the planets are 3/16 of a circle, i.e., 108°, apart. Cf. DECILE.
1647. Lilly, Chr. Astrol., iii. 32. Of late one Kepler, a learned man, hath added some new ones as follow … A Tredecile … consisting of 108 degrees.
1674. Jeake, Arith. (1696), 11. Aspects…. Sesquiquintil or Tredecil.
1727–47. Chambers, Cycl., Aspect, To the five ancient aspects, the modern writers have added several more; as decile,… tridecile,… [etc.].
1819. J. Wilson, Compl. Dict. Astrol., 101. The new aspects invented by Kepler are mostly produced by subdividing the others…. The Tredecile, of 108°, is a quintile and half, or three deciles…. Those arising from a division of the Δ or * by 5 were [thought by Kepler to be] good; thus … the tredecile, being a quintile and a half, is good.
