Third person singular present tense; blocks up or clogs completely.
Third person singular present tense of beclog, formed with -s suffix.
Words like 'beclogs' are barely used anymore—they sound to modern readers like Shakespearean or Victorian English. But the be- prefix system was so productive in earlier centuries that people could casually coin new words like this, and most of them simply died out when English streamlined its vocabulary.
Complete word intelligence in one call. Free tier — 50 lookups/day.