forward/forwards

backward/backwards
upward/upwards
downward/downwards
inward/inwards
outward/outwards
eastward/eastwards
westward/westwsrds
rightward/rightwards
leftward/leftwards
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Are both interchangable?
Which ones are from British English? Which ones are from American English?

They are interchangeable. I think backward, inward, westward, etc., are more proper. Adding the "s" on the end is more colloquial, but by common usage, is quite acceptable. I don't know which is more American or British.

The words "forward/forwards," "backward/backwards," "upward/upwards," "downward/downwards," "inward/inwards," "outward/outwards," "eastward/eastwards," "westward/westwards," "rightward/rightwards," and "leftward/leftwards" are variations of direction adverbs, commonly referred to as directional adverbs of manner. Let's break down each category and discuss their interchangeability and regional usage.

1. Forward/Forwards:
These terms are interchangeable and can be used in both British English and American English.

2. Backward/Backwards:
Both terms are interchangeable in British English, but in American English, "backward" is more commonly used.

3. Upward/Upwards:
Both terms are used interchangeably in both British English and American English, though "upwards" is more commonly used in British English.

4. Downward/Downwards:
Similarly, both "downward" and "downwards" are interchangeable and can be used in both British English and American English.

5. Inward/Inwards:
Both terms are used interchangeably in both British English and American English.

6. Outward/Outwards:
Both terms are interchangeable in British English, whereas in American English, "outward" is more commonly used.

7. Eastward/Eastwards:
Both terms are used interchangeably in both British English and American English.

8. Westward/Westwards:
Again, both terms are interchangeable in both British English and American English.

9. Rightward/Rightwards:
Both terms are used interchangeably in both British English and American English.

10. Leftward/Leftwards:
Both terms are used interchangeably in both British English and American English.

In conclusion, most of these directional adverbs are interchangeable and can be used in both British English and American English. However, there are a few exceptions: "backward" is more commonly used in American English, and "outward" is more commonly used in British English.