Given a tab-delimited file like this:
$ head train.txt
The Fulton County Grand Jury said Friday an investigation of Atlanta's recent primary election produced `` no evidence '' that any irregularities took place . AT NP-TL NN-TL JJ-TL NN-TL VBD NR AT NN IN NP$ JJ NN NN VBD `` AT NN '' CS DTI NNS VBD NN .
The jury further said in term-end presentments that the City Executive Committee , which had over-all charge of the election , `` deserves the praise and thanks of the City of Atlanta '' for the manner in which the election was conducted . AT NN RBR VBD IN NN NNS CS AT NN-TL JJ-TL NN-TL , WDT HVD JJ NN IN AT NN , `` VBZ AT NN CC NNS IN AT NN-TL IN-TL NP-TL '' IN AT NN IN WDT AT NN BEDZ VBN .
The September-October term jury had been charged by Fulton Superior Court Judge Durwood Pye to investigate reports of possible `` irregularities '' in the hard-fought primary which was won by Mayor-nominate Ivan Allen Jr. . AT NP NN NN HVD BEN VBN IN NP-TL JJ-TL NN-TL NN-TL NP NP TO VB NNS IN JJ `` NNS '' IN AT JJ NN WDT BEDZ VBN IN NN-TL NP NP NP .
`` Only a relative handful of such reports was received '' , the jury said , `` considering the widespread interest in the election , the number of voters and the size of this city '' . `` RB AT JJ NN IN JJ NNS BEDZ VBN '' , AT NN VBD , `` IN AT JJ NN IN AT NN , AT NN IN NNS CC AT NN IN DT NN '' .
The jury said it did find that many of Georgia's registration and election laws `` are outmoded or inadequate and often ambiguous '' . AT NN VBD PPS DOD VB CS AP IN NP$ NN CC NN NNS `` BER JJ CC JJ CC RB JJ '' .
It recommended that Fulton legislators act `` to have these laws studied and revised to the end of modernizing and improving them '' . PPS VBD CS NP NNS VB `` TO HV DTS NNS VBN CC VBN IN AT NN IN VBG CC VBG PPO '' .
The grand jury commented on a number of other topics , among them the Atlanta and Fulton County purchasing departments which it said `` are well operated and follow generally accepted practices which inure to the best interest of both governments '' . AT JJ NN VBD IN AT NN IN AP NNS , IN PPO AT NP CC NP-TL NN-TL VBG NNS WDT PPS VBD `` BER QL VBN CC VB RB VBN NNS WDT VB IN AT JJT NN IN ABX NNS '' .
Merger proposed NN-HL VBN-HL
However , the jury said it believes `` these two offices should be combined to achieve greater efficiency and reduce the cost of administration '' . WRB , AT NN VBD PPS VBZ `` DTS CD NNS MD BE VBN TO VB JJR NN CC VB AT NN IN NN '' .
The City Purchasing Department , the jury said , `` is lacking in experienced clerical personnel as a result of city personnel policies '' . AT NN-TL VBG-TL NN-TL , AT NN VBD , `` BEZ VBG IN VBN JJ NNS CS AT NN IN NN NNS NNS '' .
>>> fout = open('word.dict', 'w')
>>> fout.write('\n'.join(list(set(zip(*[line.split('\t').lower().split() for line in open('train.txt')])))))
$ head word.dict
cut -f1 file | tr -s '[:space:]' '\n' | tr '[:upper:]' '[:lower:]' | sort -u
cut -f1 extracts the 1st tab-separated column
tr -s '[:space:]' '\n' replaces each run of whitespace with a line break, effectively creating a list of words, each on its own line.
tr '[:upper:]' '[:lower:]' translates the lines to all-lowercase.
sort -u sorts the resulting list of words with duplicates omitted (