In the direction of the flat side; with the broad surface facing a particular direction.
Compound of 'flat' + '-wise' (a suffix meaning 'in the manner of'), used in technical descriptions of object orientation.
The '-wise' suffix (like in 'clockwise' or 'lengthwise') lets you describe orientation precisely—'flatwise' tells you exactly how something is angled.
Complete word intelligence in one call. Free tier — 50 lookups/day.