The appellant in the new case can be either the plaintiff (or claimant), defendant, third-party intervenor, or respondent (appellee) from the lower case, depending on who was the losing party.
ðɪ ɐpˈɛlənt ɪnðə nˈuː kˈeɪs kæn biː ˈiːðɚ ðə plˈeɪntɪf ɔːɹ klˈeɪmənt, dᵻfˈɛndənt, θˈɜːdpˈɑːɹɾi ˌɪntɚvˈɛnɚ, ɔːɹ ɹᵻspˈɑːndənt ɐpˈɛliː fɹʌmðə lˈoʊɚ kˈeɪs, dᵻpˈɛndɪŋ ˌɔn hˌuː wʌzðə lˈuːzɪŋ pˈɑːɹɾi.