This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. Acting to supplement.

adj. Appending.

adj. Lacking a regular schedule (as in a supplemental airline).

n. Something that supplements or adds to.

n. A requisition or article of legislation that provides additional funding for a program.

adj. Added to supply what is wanted; additional; being, or serving as, a supplement.

Of the nature of a supplement; serving to supplement; additional; added to supply what is wanted.

adj. functioning in a supporting capacity

adj. added to complete or make up a deficiency

"Iraq's electrical infrastructure, which is the number one line item in the spending package, what we call the supplemental package for the reconstruction of Iraq."

secondary    additive    supplementary   

supplemental cusp    supplemental cone    pleading    supplemental arcs    supplemental air    supplemental versed sine    supplemental chords   

supplementally   

additional   

Occidental    Oriental    accidental    coincidental    compartmental    continental    dental    departmental    detrimental    developmental   

supplementary    dietary    additional    adequate    discretionary    quarterly    marginal    cumulative    biographical    recommend