Synonym: by all odds, definitely, emphatically, in spades, unquestionably. Similar words: decided, undecided, decide, decide on, deciduous, aide-de-camp, acidly, forcedly. Meaning: [-dɪdlɪ] 
adv. without question and beyond doubt.
adv. without question and beyond doubt. 
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1. The local provision of facilities is decidedly patchy.
2. She had a decidedly down-at-heel appearance.
3. She had a decidedly murky past.
4. It all sounds decidedly risky to me.
5. Make up your mind to act decidedly and take the consequences. No good is ever done in this world by hesitation.
6. Cole's style is decidedly more formal than the previous manager's.
7. I feel decidedly unwell this morning.
8. She was decidedly cool about the proposal.
9. His musical achievements have been decidedly slender.
10. The milk smells/tastes decidedly off.
11. She was decidedly cool towards me.
12. Lunch was a decidedly unglamorous affair.
13. That coat is looking decidedly past it.
14. Their relationship is beginning to look decidedly shaky.
15. The atmosphere in the room was decidedly frosty.
16. 'I'm not going to do it,[sentencedict.com]' said Margaret decidedly.
17. The options were decidedly unattractive.
18. The future looked decidedly gloomy.
19. 'I won't go,(http://sentencedict.com)' she said decidedly.
20. An agreement is looking decidedly difficult according to the newspapers.
21. Sometimes he is decidedly uncomfortable at what he sees on the screen.
22. I came from a family that was decidedly oddball you know.
23. The result is a decidedly mixed bag of campy humor, wild-eyed fantasy and high-tech special effects.
24. Amy was looking decidedly worried.
25. Discs' efforts in this direction have been decidedly half-hearted.
26. Some managers were decidedly uneasy about the changes.
27. In everyday speech it is a decidedly negative word.
28. He made all the other players on the field look decidedly ordinary.
29. There was a fulcrum point when the arguments tipped decidedly in one direction.
30. The intervention of the authorities gave union struggles a decidedly political flavour.
More similar words: decided, undecided, decide, decide on, deciduous, aide-de-camp, acidly, forcedly, fixedly, lucidly, allegedly, markedly, doggedly, placidly, supposedly, hurriedly, assuredly, reputedly, composedly, excitedly, devotedly, pointedly, resignedly, dejectedly, reportedly, admittedly, agitatedly, perplexedly, unabashedly, repeatedly.