the word "straightaway" is a transparent compound formed from two native english elements. "straight," meaning direct or without deviation, combines with "away," implying motion or direction from a point. the literal sense of 'a direct path away' evolved into its adverbial meaning of proceeding immediately and directly, without any detour or hesitation. this logical progression from a physical description to a temporal one is characteristic of english compounding, where spatial concepts are readily applied to abstract notions of time and manner.

Structure: straight + away "straight" (from middle english streght, from old english streht, meaning 'direct, not curved', of germanic origin). "away" (from old english aweg, onweg, meaning 'on one's way, from this or that place', of germanic origin).