"Doubleness" is the quality or state of being double or having two parts. Synonyms for this word include duplicity, duality, dichotomy, twofoldness, and ambivalence. Duplicity refers to the act of being deceitful or dishonest, while duality suggests the existence of two opposing forces or ideas. Dichotomy implies a division or contrast between two things. Twofoldness highlights the concept of doubling or being twice as much, and ambivalence suggests the coexistence of conflicting feelings or opinions. These synonyms can help to convey different shades of meaning and enhance the richness of language in writing or conversation.