Cousot & Cousot use a number of terms and notations in their abstract
interpretation paper without defining them.  Here is some information
to help you make sense of the paper.

Declaration notation ===> f : T | P
    Defines f to be a thing of type T that satisfies property P.

Semilattice
    A lattice with a well-defined `lub`, but not necessarily a well-defined
    `glb` (or vice-versa).  You will sometimes see "join semilattice" for
    one with only a `lub` operation, or "meet semilattice" for one with
    only a `glb` operation.

Complete lattice or complete semilattice
    The formal definitions are quite involved, but the key fact about complete
    lattices is that they are bounded---i.e. they have top and bottom elements
    and a finite height.

Order-preserving, isotone, monotone, monotonic
    A function f is order-preserving if (x <= y) implies (f(x) <= f(y)).
    "Isotone", "monotone", and "monotonic" are other words for order-preserving
    that you might have heard before.

Fixpoint
    A value associated with a function f such that f(x) == x.
    If f is order-preserving with respect to a lattice, then repeatedly
    applying f (see Kleene's sequence immediately below) will eventually
    arrive at some fixpoint.

Kleene's sequence
    The Kleene's sequence `k` for a function `f` is
        k_0 = [some initial value]
        k_i = f(k_{i-1})
    A finite Kleene's sequnce is one where the value eventually stops changing;
    i.e. there exists j such that k_i = k_j for all i > j.  The value k_j is
    called the "limit" of the sequence, and it is a fixpoint of f.

Semantics
    If you have not seen formal semantics for a language before, Section 3.2
    will be quite dense.  The authors are simply defining an interpreter in
    terms of mathematical constructs.