_Anther._ The part of the stamen which contains the pollen. _Anthropogeography._ The science which treats of geography as applied to man. That part of anthropology dealing with the effect of the environment on human beings. There are a number of compounds beginning with anthro-. The meaning may often be understood by remembering that the Greek word _anthropos_ means man, not as opposed to woman but as excluding the non-human. _Anthropology._ The study of man as an animal, with respect to race, distribution, culture, and social organization. _Anticlinal._ Forming a ridge with strata leaning in opposite directions from an axis. Having an upright spine toward which spines on both sides lean. _Anticyclone._ An outward and rotary flow of air from an atmospheric area of high pressure. _Antidote._ A medicine used to counteract a poison or disease. _Antimony._ An element of metallic appearance. Symbol: Sb. _Anus._ The posterior opening of the alimentary canal. _Apetalous._ Without petals. _Aphasia._ Loss of speech from a brain injury. _Aphelion._ The point in the orbit of a planet or comet farthest from the sun. _Apheliotropic._ Turning away from the sun. _Apogee._ The point in the orbit of a planet or the moon where it is farthest from the earth. _Aponeurosis._ The flat, dense connective tissue covering and forming the attachments of certain muscles. _Aquatic._ Growing or living in or near the water. _Arachnida._ A class of animals including spiders and scorpions. _Arachnoid._ Covered with long, thin hairs. A serous membrane enveloping the brain and spinal cord. _Arboreal._ Living in or connected with trees. _Archeology._ The study of prehistoric antiquity, or sometimes of antiquity which is not prehistoric. _Archean._ Also: Archaean. Relating to the earliest geological period. _Arenicolous._ Living in the sand. _Argon._ A gaseous element found in the atmosphere in small amounts. Symbol: A. _Arsenic._ A semi-metallic element. Symbol: As. _Art._ Skill of various sorts. Knowledge from the practical point of view. H. W. Fowler distinguishes it from science: “Science knows, art does; a science is a body of connected facts, an art is a set of directions; the facts of science (errors not being such) are the same for all people, circumstances, and occasions; the directions of art vary with the artist and the task.” According to the Oxford English Dictionary: “The distinction as commonly apprehended is that a science is concerned with theoretic truth, and an art with methods for effecting certain results. Sometimes, however, the term _science_ is extended to denote a department of practical work which depends on the knowledge and conscious application of principles; an art, on the other hand, being understood to require merely knowledge of traditional rules and skill acquired by habit.” _Articulation._ A joint, as between bones or parts of plants, especially between parts which may separate at any time.