What is the meaning of Hm?

Symbol for hectometer , an SI unit of length equal to 10 meters .

A shorter variant of hmm.

A letter of the Aleut alphabet, written in the Latin script.

Hanyu Pinyin reading of

same, similar

hmm

meh

hmm

hm (expressing confusion, annoyance, etc.)

hm (indicating thinking or pondering)

erm (expression of uncertainty)

what?

Source: wiktionary.org