On gloss:

sumji
x1 is a mathematical sum/result/total of x2 plus/increased by x3.

On affix form:

sumti
x1 is a/the argument of predicate/function x2 filling place x3 (kind/number).

In definition:

grisumji
x1 is the sum (combined addition result) of x2 (plurality of the same type as x1)
gu'y (exp!)
predicate modifier: convert x1 to a mereological sum composed of x1.
pelmeni
x1 is a piece/pieces of dumplings/ravioli/pelmeni/dim sum (Hongkong/Xianggang cuisine) containing x2
porsumji
x1 is the sum of all the members of the number sequence x2
pu'e'ei (exp!)
mekso binary operator: generate span; outputs span(X1, X= spanX; set of all (finite) sums of terms of form c v, where v is an element of algebraic structure X1 (wherein scalar multiplication and summation is defined), and c is a scalar belonging to ring X2.
sau'i (exp!)
mekso n-ary operator: reciprocal of the sum of the reciprocal of each of X1, X2, ..., Xn (for any natural number n); 1/((1/X1) + (1/X.
selcmimau
c2=z1 exceeds/is more than the sum of its parts c1=z2 in property/quantity z3 (ka/ni) by amount/excess z4
simsumji
x1 is the sum of all of x2 added together
sujypau
p1 is a term of sum/polynomial p2=s1
tai'i'au (exp!)
8-ary mekso operator: the X1th nonnegative sum of X2 mutually-distinct perfect X3th-powers (i.e.: of integers) in X4 mutually truly-distinct ways, requiring exactly X5 terms to be negative in each sum (counting with(out^X6) multiplicity), requiring exactly X7 terms to be repeated between sums (counting with(out^X8) multiplicity), according to the usual ordering of the integers.
unma
x1 is the group/aggegate/mereological sum made of x2 and nothing else.
zumji'e
x1 is x2's life (course of existence, sum of experiences and actions)

In notes:

cnanfadi
x1 (li; number/quantity) is the weighted quasi-arithmetic mean/generalized f-mean of/on data x2 (completely specified ordered multiset/list) using function x3 (defaults according to the notes; if it is an extended-real number, then it has a particular interpretation according to the Notes) with weights x4 (completely specified ordered multiset/list with same cardinality/length as x2; defaults according to Notes).
cnanlime
x1 is the generalized weighted Lehmer mean of data x2 (completely specified ordered multiset/list of numbers) of Lehmer order x3 (either a single extended-real number xor an ordered pair of two extended-real numbers) with weights x4 (completely specified ordered multiset/list of numbers with the same cardinality as x2; defaults according to the Notes).
di'ei'o'au (exp!)
mathematical ternary operator: Dirichlet convolution (a×b)(c)
fancufacki
x1 (person/computer/agent) finds the result of applying mathematical function/operator x2 to arguments x3 (ordered list)
fei'i (exp!)
mekso variable-arity (at most ternary) operator: number of prime divisors of number X1, counting with or without multiplicity according to the value X2 (1 xor 0 respectively; see note for equality to -1 and for default value), in structure X3.
fi'au
mekso operator: continued fraction, Kettenbruch notation; for ordered input (X1, X, where: X1 is an ordered pair of functions and X2 is a free or dummy variable/input/index which ranges through set X3 in order(ing) X4, the result is K(X for Kettenbruch notation K.
ga'au (exp!)
digit/number: Euler–Mascheroni constant, usually denoted by lowercase gamma (γ); approximately 0.5772156649 (in decimal).
ji'i'u (exp!)
mekso, at-most-5-ary operator: a rounding function; ordered input list is (x,n,t,m,b) and the output is sgn(x) bt roundn (b(-t) abs(x)), with rounding preference n and where the fractional part of b(-t) abs(x) being equal to 1/2 causes the roundn ( ) function to map b(-t) abs(x) to the nearest integer of form 2Z+m, for base b (determined by context if not explicitly input) and some integer Z (determined by context).
kei'au
mekso operator: finite result set derived from/on set A with/due to operator/function B under ordering of application C
ma'au (exp!)
Binary mekso operator: uniform probability A(X2)u(X for input (X1,X where X1 is a number and X2 is a set or space. (See notes for details).
mai'e'e (exp!)
digit/number: Meissel-Mertens constant M ≈ 0.2614972128476427837554268386086958590516…
moxna
x1 is not enough/an insufficient amount/too little/too few of x2 by standard x3.
ni'e'oi (exp!)
digit/number: Niven's smallest-exponent prime factorization constant c = zeta(3/2)/zeta(3) ≈ 2.1732543125195541382370898404…
salri
x1 is the differintegral of x2 with respect to x3 of order x4, with differintegration being according to definition/specification or of type x5.
salrixo
x1 is the differintegral of x2 with respect to x3 of order x4, with differintegration being according to definition/specification or of type x5.
tefsujme'o
m1 is a polynomial function in variable t2=s2 of degree (maximum power with nonzero coefficient) t3 interpreted by rules m2
xoi'ei'a
Toggles grammar so that every mention of a number n is interpreted as "at least n".
zo'u'e
Generalized prenex/topic separator/joiner; such that …