Aboard - abroad
Do not confuse abroad with aboard. This is an easy typing error to make, but can be hard to spot.
- Abroad means 'foreign', or 'in the big wide world'. It originally meant something similar to the modern 'at large': "a[t] broad".
- Aboard means 'on a ship', or some other means of transport. It can also be used figuratively, to mean something like 'accompanying' or 'part of a team'.
Be careful, too, not to insert an extra space. "A [space] broad" is a rather old-fashioned US slang word for 'a woman', particularly 'a girlfriend' (or potential girlfriend).
See also board - broad.