Used to indicate the means, method, way, or manner of doing something / Used to indicate the location or place where an action takes place / Used to indicate the reason or cause behind an action

(informal) indicating the following sentence is a consequence of something previously stated: and then; therefore

is/am/are ... and: the て-form or conjunctive form of だ (da)

The hiragana syllable で (de). Its equivalent in katakana is デ (de).

at / by means of

(Classical Japanese, archaic) Attaches to the 未然形 (mizenkei, “irrealis or incomplete form”) of verbs to form the negative conjunctive, equivalent to the modern ないで (-naide) or ずに (-zuni).

(dialectal, chiefly Kansai) sentence-ending particle signifying emphasis

(Kyūshū or informal) It is indeed so. / Yes.

misreading of 云々 (unnun, “and so on”)

slovenly, sloppily, in the manner of a slob / swooningly, fawningly, schmoozingly, flirtingly (especially regarding a man's behavior towards women)