佇 (Tī)熱力學 (jia̍t-le̍k-ha̍k)內 (lāi)，一 (chi̍t)个 (ê)系統 (hē-thóng)內的 (ê)內能 (lōe-lêng) (內能; internal energy) 是 (sī)彼个 (hit-ê)系統內所 (só͘)有含 (ū-hâm)的能量 (lêng-liōng); 遮的 (chia-ê)能量包含 (pau-hâm)系統內的位能 (ūi-lêng)佮 (kap)動能 (tōng-lêng)。