call to remembrance; keep alive the memory of someone or something, as in a ceremony; "We remembered the 50th anniversary of the liberation of Auschwitz"; "Remember the dead of the First World War"
be or provide a memorial to a person or an event; "This sculpture commemorates the victims of the concentration camps"; "We memorialized the Dead"
mark by some ceremony or observation; "We marked the anniversary of his death"
based on custom rather than documentation; "an unwritten law"; "rites...so ancient that they well might have had their unwritten origins in Aurignacian times"- J.L.T.C.Spence
articulate (a consonant) with the tongue curled back against the palate; "Indian accents can be characterized by the fact that speakers retroflex their consonants"