Overflowing means so full that it is spilling over the edges. A bath, a bin, a river after a week of rain.
The literal sense is about liquid or contents going past the rim, and the verb overflow works alone or with with. The figurative sense is warm and very common, since somebody overflowing with enthusiasm or gratitude has more of it than they can contain. English has a nice fixed phrase in filled to overflowing. Rivers give us the related noun a floodplain, and the thing that lets water escape safely is an overflow.
1adjectiveoverflowingSo full that the contents are spilling out.
“The bin was overflowing by Friday.”
2adjectivestrongFull of a strong feeling.
“She was overflowing with plans for the summer.”
Too few real examples of this word to estimate which sense is commonest.
Old English
oferflōwan
Middle English
overflowen
English
overflow
English, today
overflowing
From overflow + -ing. overflow comes from Middle English overflowen, from Old English oferflōwan, equivalent to over- + flow.
Etymology from Wiktionary, CC BY-SA