diagonal is a valid English word

Scrabble validity: valid ( international - Sowpods, US - Twl06 )
iScramble validity: valid
QuickWords validity: valid

Meanings

Adjective (NOT COMPARABLE)

(geometry) Joining two nonadjacent vertices (of a polygon or polyhedron).
Having slanted or oblique lines or markings.
Having a slanted or oblique direction.

Noun (COUNTABLE)

(geometry) A line joining non-adjacent vertices of a polygon.
Anything forming or resembling such a line, particularly:

diagonal is a Scrabble valid word

d2i1a1g2o1n1a1l1

• International English (Sowpods) - The word is valid in Scrabble ✔
• US English (TWL06) - The word is valid in Scrabble ✔
• 10 points

diagonal is an iScramble, QuickWords valid word

d1i2a3g4o5n6a7l8

• The word is valid in iScramble ✔
• The word is valid in QuickWords ✔
• 36 points

Same letters words (Anagrams)

• GANOIDAL
• GONADIAL

Same letters plus one

• AGUINALDO
• ALBONDIGA
• BADOGLIAN
• DIAGONALS
• DIAGONIAL
• GADOLINIA
• GALAGONID
• GIRANDOLA

Same letters minus one

• AGAONID
• ALOGIAN
• ANGLOID
• DALGONA
• DIGONAL
• GALIANO
• GALINDO
• GONADAL
• LOADING
• LOGANIA