plene spelling

Plene (or full) spelling is the opposite of defective spelling.  The letters vav and others are used as full vowels. See the glossary in KHW p. 373.  video
For example, the word,

יוֹשֵב

is different than the same word

יֹשֵב

The first word is plene spelling since the vav is preserved as a vowel. The second is not.