# What is a Doubtful Word™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles.

If a word conforms to a special rule, I call it a Doubtful Word™.

Use the following examples below to find the rule.

Here is a CSV version:

DOUBTFUL WORD™, NOT DOUBTFUL WORD™
FORAGE, HUNT
ONION, GARLIC
OTHERWISE, DIFFERENT
IMAGE, PICTURE
LITERATE, LIBRARY
WITLESS, STUPID
INFANCY, YOUTH
MICROSCOPE, ZOOM
FRIENDSHIP, ALLIANCE
SUBSCRIBE, REGISTER
ATROPHY, WASTE
BACKWARDS, REAR

• You might consider removing READER from the list of Not Doubtful Words, since Oxford English Dictionary (one of two big authorities on English) lists ER as an exclamation. – GoldenGremlin Jan 30 '17 at 18:51
• WAS TE is also splittable. – Rubio Jan 30 '17 at 19:56
• Does it have anything to do with word occurrence frequency in a text corpus/ngrams? – Buffer Over Read Jan 30 '17 at 20:42
• @CipherRiddle no – Melkor Jan 30 '17 at 20:44

A Doubtful Word is

A word that can be split into two substrings both of which are also words, whereas Not Doubtful words cannot.
For example:
"Atrophy" -> "A" + "Trophy", or
"Literate" -> "Liter" + "Ate".

As such if spacing is unclear we may be doubtful about the intended meaning of Doubtful Words; we may be unsure if they are one word or two.

The exceptions I see are slightly obscure:

"Reverse" -> "Re" + "Verse".
The somewhat new word "Re" came up in another puzzle recently too, but it seems to have crept into the English language as it is used to specify that the following text is regarding some referenced subject.

"Zoom" -> "Zo" + "Om".
"Zo" - a Tibetan breed of cattle, developed by crossing the yak with common cattle (only the "dzo" spelling is in the O.E.D., but "zo" is in Collins as a variant).
"Om" - the most sacred mantra in Hinduism and Tibetan Buddhism.

Others pointed out by Silenus and Rubio (respectively) are:

"Er" - a natural utterance, when one hesitates.

"Waste" -> "Was" + "Te".
"Te" - the syllable used for the seventh note or subtonic of any scale (As in "do-re-mi-fa-so-la-te-do" and variants thereof),

OP edit:

It's a doubtful word, because it is unsure, it has "split" opinions.

• Didn't posted the answer due to the "re" factor. I guess there is something else in there which makes it doubtful. – Techidiot Jan 30 '17 at 18:36
• Reverse could also be Rev (as in revving up an engine) + Erse (an old word for Gaelic). – M Oehm Jan 30 '17 at 18:39
• Answer is correct good work! Sorry about the "re" thing I wasn't aware of this being a real formal word (ignore it). To be accepted try to explain why it's doubtful. – Melkor Jan 30 '17 at 18:40
• Doubtful, perhaps because it also contains two words. Doubt and Full? (Ful=Full, maybe) – Sid Jan 30 '17 at 18:47
• @MOehm "rev" an abbreviation (yours is of "revolution" but also of "reverend" [clerical] or "Revelations" [book of the bible]) . – Jonathan Allan Jan 30 '17 at 18:55