one single term for both definitions

It refers to security gaps (network security holes, or simply network holes) that make a network vulnerable to attack by hackers.

Italian definitions at hyperlink reference.
Google to check English - e.g. Power protection basics
... even with a varying input voltage and provides ... experiences a significant power surge
or complete outage. ... adequate protection as long as power sags or outages ...
www.continuitycentral.com/feature039.htm
and- Power and Energy Management:
... Are transients, sags, surges, or outages, causing productivity loss ... are for true
RMS AC voltage and current trend recording, together with power quality, surge ...
www.rhopoint.co.uk/systems/powermn.htm

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Note added at 2004-02-19 08:36:19 (GMT)
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Interruzioni dell\'alimentazion- voltage less than 1% of normal value
Interruzioni lunghe - greater than 3 minutes
Interruzioni brevi - less than 3 minutes
Buchi di tensione – voltage between 90% and 1% of normal value for between 10 milliseconds and 1 minute
Sags - low voltage for half-cycle (10 milliseconds) to, typically, a few seconds - www.marcspages.co.uk/pq/1000.htm www.umist.ac.uk/departments/mcee/research/Publications/stor...

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Note added at 2004-02-19 11:41:34 (GMT)
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A sag or dip, as defined by IEEE Standard 1159-1995, IEEE Recommended Practice for Monitoring Electric Power Quality, is a decrease in rms voltage or current at the power frequency for durations from 0.5 cycles to 1 minute (www.remotepq.com/faq.html and various other Google hits)

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Note added at 2004-02-19 11:56:47 (GMT)
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When the supply voltage has been zero for a period of time in excess of 1 minute, the long duration voltage variation is considered a sustained interruption. Voltage interruptions longer than one minute are often permanent and require human intervention to repair the system for restoration. The term sustained interruption refers to specific power system phenomena and, in general, has no relation to the usage of the term outage. Utilities use outage or interruption to describe phenomena of similar nature for reliability reporting purposes. However, this causes confusion for end users who think of an outage as any interruption of power that shuts down a process. This could be as little as one-half of a cycle. Outage, as defined in IEEE Std 1008, does not refer to a specific phenomenon, but rather to the state of a component in a system that has failed to function as expected. Also, use of the term interruption in the context of power quality monitoring has no relation to reliability or other continuity of service statistics. Thus, this term has been defined to be more specific regarding the absence of voltage for long periods. www.ece.umr.edu/courses/w03/ee304/Def/PQnetwork/long_var.ht...
Looks as if “(sustained) interruptions and sags/dips” is about it.

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Note added at 2004-02-19 12:09:20 (GMT)
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IEEE Standard 1159-1995 ..... Also, 1159 suggests that the terms sag, swell, and interruption be preceded by a modifier describing the duration of the event (instantaneous, momentary, temporary, or sustained). ..... grouper.ieee.org/groups/sag/IEEEP1564_99_02.doc

Most commonly used terms in power analysis instruction manuals