The instructions of a pattern can be written as detailed explanations of each step, or as charts and sometimes a combination of both. To make the detailed explanations shorter we use abbreviations.
Here you can find the most common abbreviations you can find in a pattern.
General:
alt – alternative
approx – approximately
beg – begin / beginning
bet – between
blo (bl) – back loop only
BOR – beginning or round/ row
bp – back post
CC – contrasting colour
ch-sp – chain space
cl – cluster
cm – centimeter
cont – continue
dec – decrease
dir – directions
est – established
ex – extended
flo (fl) – front loops only
FO – Fasten off / finish off / finished object
foll – following
fp – front post
g – grams
in – inch
inc – increase
inst – instruction
lp – loop(s)
m – marker / meters
MC – main colour / magic circle
meas – measures
mm – millimetre
mr – magic ring
mult – multiple
pat – pattern
pat st – pattern stitch
pm – place marker
prev – previous
r – row/ round
rem – remaining
rep – repeat
rev – reverse
rnd(s) – round(s)
RS – right side
sk – skip
sm – slip marker
sp – space
st(s) – stitch(es)
tog – together
Ws – wrong side
yd – yarn
yo(h) – yarn over (hook)
yu – yarn under
Stitches:
ch – chain
US: slip stitch (sl st) – UK: slip stitch (ss)
US: single crochet (sc) – double crochet (dc)
US: half double crochet (hdc) – half treble (htr)
US: half treble double crochet (dc) – treble (tr)
US: double crochet (treble (tr) – double treble (dtr)
US: double treble (dtr) – triple treble (trtr)
p – picot
In addition to the above abbreviations, you will find combinations of these, for example:
bpdc – back post double crochet
scflo – single crochet in the front loop only
hdc2tog – half double crochet 2 together (decrease one stitch)
Of course it is not possible to make a complete record of all the abbreviations that exist. If you come across one that is not in the list, please write it in the comments, and I will add it.