Selective serotonin reuptake inhibitor. Selective serotonin reuptake inhibitors (SSRIs), also known as serotonin-specific reuptake inhibitors or serotonergic antidepressants,[1] are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder and anxiety disorders.
Then you're looking for the midpoint! The midpoint of a line segment is the point located midway between the endpoints of the line segment. This tutorial tells you about the midpoint of a line segment.
midpoint. 1  a point at or near the middle of, or equidistant from, both ends, as of a line: the midpoint of a boundary. 2  a point in time halfway between the beginning and the end, as of a process, event, or situation: the midpoint of the negotiations. Geometry. the point on a line segment or an arc that is equidistant, when measured along the line or the arc, from both endpoints.