A katakana expression corresponding to English “how.” In ordinary Japanese questions, use どう or どのように instead; ハウ is mostly limited to English-learning, transcription, titles, or quoted English.
The “How” in the English phrase “How are you?” is written in katakana as ハウ.
Only the katakana form ハウ and the gloss “how” are given; no language-of-origin information is specified. It is best understood here as a katakana representation corresponding to English “how,” but no further historical derivation is specified.