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

• Lexulous
• Wordscraper
• Wordosaur

adj. of, or relating to a foundation or foundations

adj. fundamental or underlying

Of the nature of a foundation; fundamental.

"Going forward, we are looking at a few key areas for investment in Afghanistan, what we call our "foundational investments.""

fundamental    basic    basal   

Congregational    aberrational    coeducational    computational    conformational   

postsecondary    ontological    synthetical    methodological    cosmogonic