We don't have synonyms for symmedian yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are submedian, symmetrian and symmelia.
(n) :
(geometry) Any of three lines associated with every triangle, constructed by taking a median of the triangle (a line connecting a vertex with the midpoint of the opposite side) and reflecting the line over the corresponding angle bisector (the line through the same vertex that divides the angle there in half).
(n) :
(geometry) Any of three lines associated with every triangle, constructed by taking a median of the triangle (a line connecting a vertex with the midpoint of the opposite side) and reflecting the line over the corresponding angle bisector (the line through the same vertex that divides the angle there in half).