Meanings of abbreviations follow. From JMdict. Some may be unused. Unsorted.

MA - martial arts term
X - rude or X-rated term (not displayed in educational software)
abbr - abbreviation
adj-i - adjective (keiyoushi)
adj-ix - adjective (keiyoushi) - yoi/ii class
adj-na - adjectival nouns or quasi-adjectives (keiyodoshi)
adj-no - nouns which may take the genitive case particle `no'
adj-pn - pre-noun adjectival (rentaishi)
adj-t - `taru' adjective
adj-f - noun or verb acting prenominally
adv - adverb (fukushi)
adv-to - adverb taking the `to' particle
arch - archaism
ateji - ateji (phonetic) reading
aux - auxiliary
aux-v - auxiliary verb
aux-adj - auxiliary adjective
Buddh - Buddhist term
chem - chemistry term
chn - children's language
col - colloquialism
comp - computer terminology
conj - conjunction
cop-da - copula
ctr - counter
derog - derogatory
eK - exclusively kanji
ek - exclusively kana
exp - expressions (phrases, clauses, etc.)
fam - familiar language
fem - female term or language
food - food term
geom - geometry term
gikun - gikun (meaning as reading) or jukujikun (special kanji reading)
hon - honorific or respectful (sonkeigo) language
hum - humble (kenjougo) language
iK - word containing irregular kanji usage
id - idiomatic expression
ik - word containing irregular kana usage
int - interjection (kandoushi)
io - irregular okurigana usage
iv - irregular verb
ling - linguistics terminology
m-sl - manga slang
male - male term or language
male-sl - male slang
math - mathematics
mil - military
n - noun (common) (futsuumeishi)
n-adv - adverbial noun (fukushitekimeishi)
n-suf - noun, used as a suffix
n-pref - noun, used as a prefix
n-t - noun (temporal) (jisoumeishi)
num - numeric
oK - word containing out-dated kanji
obs - obsolete term
obsc - obscure term
ok - out-dated or obsolete kana usage
oik - old or irregular kana form
on-mim - onomatopoeic or mimetic word
pn - pronoun
poet - poetical term
pol - polite (teineigo) language
pref - prefix
proverb - proverb
prt - particle
physics - physics terminology
rare - rare
sens - sensitive
sl - slang
suf - suffix
uK - word usually written using kanji alone
uk - word usually written using kana alone
unc - unclassified
yoji - yojijukugo
v1 - Ichidan verb
v1-s - Ichidan verb - kureru special class
v2a-s - Nidan verb with 'u' ending (archaic)
v4h - Yodan verb with `hu/fu' ending (archaic)
v4r - Yodan verb with `ru' ending (archaic)
v5aru - Godan verb - -aru special class
v5b - Godan verb with `bu' ending
v5g - Godan verb with `gu' ending
v5k - Godan verb with `ku' ending
v5k-s - Godan verb - Iku/Yuku special class
v5m - Godan verb with `mu' ending
v5n - Godan verb with `nu' ending
v5r - Godan verb with `ru' ending
v5r-i - Godan verb with `ru' ending (irregular verb)
v5s - Godan verb with `su' ending
v5t - Godan verb with `tsu' ending
v5u - Godan verb with `u' ending
v5u-s - Godan verb with `u' ending (special class)
v5uru - Godan verb - Uru old class verb (old form of Eru)
vz - Ichidan verb - zuru verb (alternative form of -jiru verbs)
vi - intransitive verb
vk - Kuru verb - special class
vn - irregular nu verb
vr - irregular ru verb, plain form ends with -ri
vs - noun or participle which takes the aux. verb suru
vs-c - su verb - precursor to the modern suru
vs-s - suru verb - special class
vs-i - suru verb - irregular
kyb - Kyoto-ben
osb - Osaka-ben
ksb - Kansai-ben
ktb - Kantou-ben
tsb - Tosa-ben
thb - Touhoku-ben
tsug - Tsugaru-ben
kyu - Kyuushuu-ben
rkb - Ryuukyuu-ben
nab - Nagano-ben
hob - Hokkaido-ben
vt - transitive verb
vulg - vulgar expression or word
adj-kari - `kari' adjective (archaic)
adj-ku - `ku' adjective (archaic)
adj-shiku - `shiku' adjective (archaic)
adj-nari - archaic/formal form of na-adjective
n-pr - proper noun
v-unspec - verb unspecified
v4k - Yodan verb with `ku' ending (archaic)
v4g - Yodan verb with `gu' ending (archaic)
v4s - Yodan verb with `su' ending (archaic)
v4t - Yodan verb with `tsu' ending (archaic)
v4n - Yodan verb with `nu' ending (archaic)
v4b - Yodan verb with `bu' ending (archaic)
v4m - Yodan verb with `mu' ending (archaic)
v2k-k - Nidan verb (upper class) with `ku' ending (archaic)
v2g-k - Nidan verb (upper class) with `gu' ending (archaic)
v2t-k - Nidan verb (upper class) with `tsu' ending (archaic)
v2d-k - Nidan verb (upper class) with `dzu' ending (archaic)
v2h-k - Nidan verb (upper class) with `hu/fu' ending (archaic)
v2b-k - Nidan verb (upper class) with `bu' ending (archaic)
v2m-k - Nidan verb (upper class) with `mu' ending (archaic)
v2y-k - Nidan verb (upper class) with `yu' ending (archaic)
v2r-k - Nidan verb (upper class) with `ru' ending (archaic)
v2k-s - Nidan verb (lower class) with `ku' ending (archaic)
v2g-s - Nidan verb (lower class) with `gu' ending (archaic)
v2s-s - Nidan verb (lower class) with `su' ending (archaic)
v2z-s - Nidan verb (lower class) with `zu' ending (archaic)
v2t-s - Nidan verb (lower class) with `tsu' ending (archaic)
v2d-s - Nidan verb (lower class) with `dzu' ending (archaic)
v2n-s - Nidan verb (lower class) with `nu' ending (archaic)
v2h-s - Nidan verb (lower class) with `hu/fu' ending (archaic)
v2b-s - Nidan verb (lower class) with `bu' ending (archaic)
v2m-s - Nidan verb (lower class) with `mu' ending (archaic)
v2y-s - Nidan verb (lower class) with `yu' ending (archaic)
v2r-s - Nidan verb (lower class) with `ru' ending (archaic)
v2w-s - Nidan verb (lower class) with `u' ending and `we' conjugation (archaic)
archit - architecture term
astron - astronomy, etc. term
baseb - baseball term
biol - biology term
bot - botany term
bus - business term
econ - economics term
engr - engineering term
finc - finance term
geol - geology, etc. term
law - law, etc. term
mahj - mahjong term
med - medicine, etc. term
music - music term
Shinto - Shinto term
shogi - shogi term
sports - sports term
sumo - sumo term
zool - zoology term
joc - jocular, humorous term
anat - anatomical term