Most of my work has been done in Hebrew where describing a spelling as "defective" is common and accepted. Is this wording current in other areas of linguistics or would something like "(not) spelled phonetically" be better?
A "defective" spelling in Hebrew is one without matres lectionis. This term exists in Hebrew because Hebrew is an abjad which doesn't always mark vowels, and consequently, words can be spelled either plene (with matres lectiones) or defective (without).
The term "defective" is also used of an orthography that can't represent all of its phonemes (defective script). For example, English spells both /θ/ and /ð/ as th. It would be correct to say that English has a defective orthography, but not that that is a defective spelling for not distinguishing the two dental fricatives.
Apart from that, words that aren't spelled phonetically aren't usually called "defective." For example, the English word busy is pronounced /ˈbɪzi/ (as opposed to */bʊzi/), but it would be incorrect to call this non-phonetic spelling "defective." /ˈbɪzi/ is also not a case of a defective orthography, because English is capable of writing bisy, but spells it differently for etymological reasons, so it could be called an etymological spelling.