bed board artifact level Mobius strip side mitre vertical surface artefact screen tread spandrel superficies ground skin plaster gameboard spandril plasterwork horizontal surface Klein bottle face projection screen silver screen miter work surface meniscus

interior substrate interface firmament palate outside vault of heaven side wavefront hard palate celestial sphere bounds welkin empyrean photosphere boundary sphere roof of the mouth exterior bound heavens end face wave front inside substratum

body of water Earth's surface geosphere gap layer water lithosphere floor opening

chemical agent active agent

progressive

operational fighting combat-ready

activity hands-on proactive activistic activeness activist

transmitter vasoconstrictive mutagen causal agent retardation impairer retardent biological agent weakener pressor causal agency invigorator satisfier cause infective agent repressor vector motor represser vasoconstrictor shortener enlivener eliminator quickener relaxer retardant teratogen biohazard stressor infectious agent lethal agent

procurator purchasing agent shipping agent next friend mill agent deputy shopper employment agent representative general agent literary agent intelligence officer special agent universal agent freight agent handler booker secret agent intelligence agent placeholder bailee government agent business agent parliamentary agent operative surrogate talent agent proxy booking agent

bacteriostat antifungal causal agent viricide antimicrobial antacid blanching agent alkalizer vermicide bleaching agent coolant drug hypoglycemic agent gastric antacid disinfectant causal agency thinner dilutant galactagogue antifungal agent coagulant lactogen nerve agent diluent mitogen virucide cause lactifuge bleach precipitant antiacid antimicrobic solvating agent emmenagogue alkaliser coagulator inducer substance antiflatulent germicide hypoglycaemic agent whitener fungicide chemical agent hypnagogue nerve gas antimycotic antimycotic agent