The Greek akmēn is an adverb meaning "still," "even now," or "at this point in time." It is used in Matthew 15:16 when Jesus expresses mild exasperation at the disciples' continued lack of understanding.
Jesus' question — "Are you still so dull?" — is a moment of pastoral patience and accountability. The disciples had walked with Jesus, witnessed miracles, heard His teaching — and yet spiritual understanding lagged. This adverb captures the reality that spiritual growth is not instant. Discipleship requires patient repetition, and the Teacher's patience is great. Yet it also carries challenge: there comes a point where continued misunderstanding, after so much instruction, becomes culpable.