English word doubtful comes from English doubt, English -ful
| Dictionary entry | Language | Definition |
|---|---|---|
| doubt | English (eng) | (ambitransitive) To lack confidence in; to disbelieve, question, or suspect.. (archaic) To fear; to suspect.. (obsolete) To fear; to be apprehensive of.. (obsolete) To fill with fear; to affright. Uncertainty, disbelief. |
| -ful | English (eng) | Used to form adjectives from nouns. Full of, tending to, or thoroughly possessing the quality expressed by the noun.. Used to form nouns from nouns meaning “as much as can be held by what is denoted by the noun”. Used to form nouns indicating a great deal of the quantity expressed by the noun. |
| doubtful | English (eng) | A doubtful person or thing. (obsolete) Fearsome, dreadful.. Experiencing or showing doubt, sceptical.. Improbable or unlikely.. Subject to, or causing doubt.. Suspicious, or of dubious character.. Unclear or unreliable.. Undecided or of uncertain outcome. |