condition, state, stamina, fitness 
[noun]
[de con-di-tie, de con-di-ties]

When a Dutch person says (s)he has a ‘bad condition’, (s)he most probably means that (s)he has ‘no stamina’ or is ‘in bad (physical) shape’. Often, ‘conditie’ in Dutch is used as a synonym for ‘voorwaarde’, in which case it refers to the terms or conditions that are part of an agreement or deal.

Note that when it regards ‘stamina’, ‘conditie’ can be used with both verbs ‘hebben’ and ‘zijn’: ‘in goede conditie zijn’, or: ‘een goede conditie hebben’.

Examples:
– “Sander probeert in goede conditie te blijven, dus na deze DWOTD gaat hij hardlopen.” 
(“Sander is trying to stay in shape, so after this DWOTD he will go running.”)

– “Dit huis is in (een) slechte conditie; ik zou er niet te veel voor bieden!” 
(“This house is in a poor state; I wouldn’t bid too much (for it)!”)

– “Na jaren gerookt te hebben, was de conditie van de man allerbelabberdst .” 
(“After having smoked for years, the man had zero stamina.” Note that the adjective ‘belabberd’ means something like ‘extremely bad’ (or: ‘rotten, lousy, rough’). The Dutch language allows for one more step in the sequence [noun]-[comparative]-[superlative], which is created by preceding the superlative with ‘aller’. So in this case ‘allerbelabberdst’ is really very very very bad.)

– “Te koop, in uitstekende conditie verkerende zeilboot. T.e.a.b.” 
(“For sale, sailing boat in excellent condition. Will accept any reasonable offer.” Note that the verb ‘verkeren’ in this case means ‘to be in’. The abbreviation ‘t.e.a.b.’ means ‘tegen elk aannemelijk bod’.)

– “Heb jij een goede of een slechte conditie?” 
(“Are you fit or unfit / off form / in bad shape?”)

– “Ok, ik ga akkoord, maar alleen onder/op de conditie dat we het verlies delen.” 
(“Ok, I agree, but only on (the) condition that we split/share the loss.”)

Related words:
– Voorwaarde: condition [noun] [de voorwaarde, de voorwaarden].
– Energie: energy [noun] [de energie, <no plural>].
– Fit: fit [adjective].
– Puf: energy, oomph [noun] [de puf, <no plural>].
– Sporten: to exercise (physically) [verb] [sportte, gesport]. Note that ‘sporten’ can be anything, exercise, fitness, practise a sport etc.