on the double (adverb) on the double: very quickly
Sinonime: awfully,
badly, decidedly,
desperately, discouragingly, disturbingly, drastically, dreadfully,
exceedingly,
extremely, fearfully, frightfully, gravely,
greatly,
highly, horribly,
intensely, markedly, mightily,
much, notoriously, remarkably,
seriously, staggeringly,
thoroughly, unbelievably, unfortunately, unhappily
Antonime: little