at this moment
Synonym discussion
Sense: idiom/1
All four phrases refer to the present, but they differ in formality and time scope. 'Right now' is the most direct and casual — it pinpoints the exact present instant ('Pick up the phone right now'). 'At this moment' is similarly precise but slightly more formal, often used when emphasising that something is happening at this exact instant. 'At present' and 'currently' refer to a broader present period — they can span days or weeks ('She is currently working on a new project'), not just the immediate second. 'At the present time' is the most formal and is common in official statements. For a single, instantaneous present point, use 'right now' or 'at this moment'; for ongoing states, use 'currently' or 'at present'.
Etymology
A prepositional phrase formed from Old English 'æt' (near, by), 'þis' (this — from Proto-Germanic *þat), and Latin 'momentum' (a movement, a short period of time) which entered English via Old French 'moment'. The phrase 'at this moment' has been used since the 14th century to refer to the present instant, with the emphatic form 'at this very moment' appearing by the 18th century.