briefly
Word family
Synonym discussion
Sense: adverb/1
'Briefly' is the most flexible choice when something happens only for a short time: 'The lights briefly went out.' 'For a moment' is common in speech and often sounds a little more personal or reflective: 'For a moment, Hana thought she was late.' 'Temporarily' usually points to a limited period that may last much longer, such as days or months: 'The library is temporarily closed.' 'Momentarily' can mean almost the same as 'briefly', but in some varieties of English it also means 'very soon', so it can be less clear. If you mean a quick action or passing change, 'briefly' is usually the safest word.
Etymology
Briefly comes from the adjective 'brief' with the adverb ending '-ly'. 'Brief' entered English through Old French from Latin 'brevis', meaning 'short'. The basic idea has stayed the same through time: something brief does not last long or does not use many words, and 'briefly' developed both of those adverb meanings in English.