English Experts

[Simon Vasconcelos]

Analfabeto funcional é uma pessoa semiafabetizada.

[Tiago Tafari Catelam]

Functional illiterate

For instance:
"Nearly Half Of Detroit's Adults Are Functionally Illiterate, Report Finds"

Source: http://www.huffingtonpost.com/2011/05/07/detroit-illiteracy-nearly-half-education_n_858307.html

More information at:
1) http://www.thefreedictionary.com/functional+illiterate

Hope it helps