fasnu -fau- gismu

x1 (event) is an event that happens/occurs/takes place; x1 is an incident/happening/occurrence.

See also fau, krefu, lifri, fatci, rapli, banli; if specifically agentive: gasnu, zukte

In definition:

fau
fasnu modal, 1st place (non-causal) in the event of ...
noi'a (exp!)
incidental/non-restrictive adverbial: converts selbri to bridi adverbial term. The first place of the converted selbri is claimed to be such that the outer bridi satisfies it, and the outer bridi is claimed. {broda noi'a brode} means {lo nu broda ku goi ko'a cu fasnu .i ko'a brode}.
poi'a (exp!)
restrictive adverbial: converts selbri to bridi adverbial term. The first place of the converted selbri is claimed to occur in conjunction with the outer bridi. {broda poi'a brode} means {lo nu broda cu fasnu gi'e brode}.

In notes:

banli
x1 is great/grand in property x2 (ka) by standard x3.
fatci
x1 (du'u) is a fact/reality/truth/actuality, in the absolute.
gasnu
x1 [person/agent] is an agentive cause of event x2; x1 does/brings about x2.
krefu
x1 (event) is the x3'rd recurrence/repetition of x2 (abstract); x2 happens again in [form] x1.
lifri
x1 [person/passive/state] undergoes/experiences x2 (event/experience); x2 happens to x1.
zukte
x1 is a volitional entity employing means/taking action x2 for purpose/goal x3/to end x3.
cabyfau
c1=f1 is live (experienced as it happens) to experiencer c2.
cazyfau
f1 is actual (existing in act or reality, not just potentially).
dorlurfau
x1 is a 'day-moon' event, a time when the moon is visible in daylight.
facfau
x1 (nu) really happens / actually happens
facnarkri
x1 is delusional, suffering from delusions; x1 has a false belief x2 (du'u) that confrontas with actual facts
fagyfau
x1 is an incident/a disaster of fire
fasnyvla
v1 is a verb meaning v2 in language v3.
faurtei
f1 is an event that has time/temporal duration t1 ranging from starting time/event t2 to ending time/event t3.
nalfau
x1 (event) is an event that doesn't happen/occur/take place
selzgaka'erfau
x1 is a phenomenon
tolfau
x1 (event) is an event that doesn't happen/occur/take place
datro
x1 (event) is dated/pertaining to day/occurring on day x2 of month x3 of year x4 in calendar x5
sfite
x1 is an appointment/date between persons (individual/mass) x2 scheduled for time x3
fi'ai (exp!)
marks end of prenex in stack-based dialect
ka'oi'i (exp!)
convert bridi into n-ary property claim: xn is such that it fills the n-th occurrence of ce'u in [bridi].
astrato
x1 is a grammatical abstraction of type x2
enfasnu
x1 happens in universe-of-discourse x2
faunli
x1 (nu) happens together with x2 (nu); x1 happens while x2 (one sense)
incipe
x1 is the beginning/the initial stage/starting/inchoate/coming into existence/first part of x2
ultime
x1 is the finale/final/last part leading up to completion of x2