SimilarityRank
compulsory 0.699 17415
mandatory 0.639 7238
be_compulsory 0.584 49804
requisite 0.541 18411
be_mandatory 0.513 18140
customary 0.495 17532
optional 0.493 6363
gratuitous 0.492 69474
the_usual 0.471 6066
required 0.451 5608
permissible 0.450 52104
superfluous 0.449 47889
stipulate 0.449 25281
be_optional 0.447 16185
an_optional 0.446 27198
oblige 0.442 24043
be_mandatory_for 0.441 51313
aforementioned 0.441 69688
an_obligation 0.439 95606
obligation 0.436 4134
full-on 0.434 99583
formality 0.426 22618
necessary 0.424 2050
a_proper 0.422 12145
it_be_mandatory 0.419 93758