中でも|なかでもnakademo[1]atamadaka (head-high)

1. expression, adverbamong (other things); especially; particularly; inter alia; above all (else)
   私は夢ゆめの中なかでも踊おどっていたと思おもいます。↗

   I think I was dancing in my sleep.

• SynonymとりわけNeutralLike 「中でも」, it singles out one thing as especially so among many, as in 「とりわけ寒い」; a touch formal for conversation but otherwise near-identical.
• Synonym殊にことにWrittenMeans 'especially; exceptionally', as in 「殊に美しい」; written in register, so it suits formal prose rather than speech.
• Synonym中にもなかにもWrittenAlmost synonymous with 「中でも」 in its 'especially among them' sense, but it leans toward written prose.
• Synonym特にとくにNeutralThe everyday, most common way to say 'especially'; unlike 「中でも」 it does not stress singling one item out of a group.
• SynonymわけてWrittenMeans 'especially; all the more'. Written in flavour and little used in modern Japanese.
• SynonymなかんずくWrittenMeans 'especially among them'; its classical kanbun-reading flavour gives it a distinctly written, literary tone.
• RelatedまずNeutralMeans 'first of all' (also 'most likely'); it stresses what comes first in sequence and does not single anything out as especially notable.
• Related何はさておきなにはさておきNeutralA set phrase meaning 'setting everything else aside, first of all'; it is about order of priority and never means 'especially among these'.
• RelatedわけてもWrittenMeans 'especially; above all'; written in flavour and used only rarely.

Use 「中でも」 to pick out the one item in a group that especially deserves mention, as in 「中でも彼が一番だ」. 「とりわけ」 also serves for 'especially'; 「特に」 is the everyday word; 「殊に」 and 「就中」 are for written prose; for 'first of all' use 「まず」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. たくさんあるなかでも特とくに。とりわけ。