What's the difference between trimeter and trimetrical?

Trimeter

Definition:

Example Sentences:

(1) (1) (2S,3R,4R,6R)-3,4-O-Carbonyl-7,7-dimethylenedithio-2,4,6-trimet hylnonane-1,3,4-triol, C15H26O4S2, M(r) = 334.49, triclinic, P1, a = 6.460 (2), b = 8.917 (3), c = 15.616 (5) A, alpha = 83.60 (3), beta = 83.41 (2), gamma = 89.52 (2) degrees, V = 888.0 (5) A3, Z = 2, Dx = 1.25 g cm-3, mu = 2.980 cm-1, lambda (Mo K alpha) = 0.7107 A, F(000) = 360, T = 298 K, R = 0.0465 for 1832 reflections [Fo greater than or equal to 4 sigma (Fo)].
(2) On the basis of 96 hr LC50 Cu was highly toxic followed by Zn and Cd, and the trimetal combination (Cu+Zn+Cd) was extremely toxic than any other combination; combination of Zn+Cd was least toxic.
(3) (2) (2S,3R,4R,6S)-3,4-O-Carbonyl-7,7-dimethylenedithio-2,4,6-trimet hylnonane-1,3,4-triol, C15H26O4S2, M(r) = 334.49, monoclinic, P21, a = 8.1849 (8), b = 8.9456 (14), c = 12.0258 (14) A, beta = 100.878 (8) degrees, V = 864.7 (2) A3, Z = 2, Dx = 1.28 g cm-3, mu = 3.060 cm-1, lambda (Mo K alpha) = 0.7107 A, F(000) = 360, T = 298 K, R = 0.0569 for 2001 reflections [Fo greater than or equal to 4 sigma (Fo)].
(4) Blood serum free fatty acid (FFA), triglyceride (TG), cholesterol and phospholipid content was studied during the 3 pregnancy trimeters in 247 pregnant women--139 suffering from diabetes mellitus without adiposity, and 108 healthy ones.

Definition:

Example Sentences:

(1) Chromatographic studies on early hGH preparations revealed the presence of dimetric, trimetric and aggregated hormone as well as small quantities of prolactin.
(2) The isolated trimetric catalytic subunit (c3) and dimeric regulatory subunit (r2) were mixed together and formation of the dodecameric native enzyme (c6r6) was monitored by measuring changes in activity.
(3) The inner layer of the rotavirus has 132 morphological units, with 260 structural units of trimetric structure.