Splitting a list based on a delimiter word

I would use a generator:

def group(seq, sep):
    g = []
    for el in seq:
        if el == sep:
            yield g
            g = []
        g.append(el)
    yield g

ex = ['A', 'WORD', 'B' , 'C' , 'WORD' , 'D']
result = list(group(ex, 'WORD'))
print(result)

This prints

[['A'], ['WORD', 'B', 'C'], ['WORD', 'D']]

The code accepts any iterable, and produces an iterable (which you don't have to flatten into a list if you don't want to).

import itertools

lst = ['A', 'WORD', 'B' , 'C' , 'WORD' , 'D']
w = 'WORD'

spl = [list(y) for x, y in itertools.groupby(lst, lambda z: z == w) if not x]

this creates a splitted list without delimiters, which looks more logical to me:

[['A'], ['B', 'C'], ['D']]

If you insist on delimiters to be included, this should do the trick:

spl = [[]]
for x, y in itertools.groupby(lst, lambda z: z == w):
    if x: spl.append([])
    spl[-1].extend(y)