triiodothyronine: thyroid hormone similar to thyroxine but with one less iodine atom per molecule and produced in smaller quantity; exerts the same biological effects as thyroxine but is more potent and briefer
matter: that which has mass and occupies space
white mangrove: shrub to moderately large tree that grows in brackish water along the seacoasts of western Africa and tropical America; locally important as a source of tannin